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Crystal Installation
New crystals for indicators and calipers

bezelandcrystal

The crystals (clear plastic lens) for test indicators, dial indicators and calipers are typically larger than the bezel for which they are designed.

New crystals are also flat. They become domed once they are inserted, under pressure. An old crystal will appear domed because, after a long time, it will take on this shape. Unfortunately, at this point it will also fall out easily.

The crystals have a beveled edge which will fit into the groove on the upper part of the bezel, but must be inserted in a concave (domed) manner so that the crystal will remain in place under pressure, and so that the plastic clears the movable dial hand.

A crystal press is usually required to give the plastic lens its concave shape. (Bestest indicators and B&S calipers are exceptions.) Place the crystal and bezel in the press, in the correct orientation (take into consideration the beveled edge: the smaller surface will become the upper surface) and while the press is bending the plastic, gently snap the bezel into place. Release the press and the crystal will be firmly seated and have the correct curvature.

The press can not be used with crystals made of glass, which will shatter under pressure.

Crystal Press shown with various inserts (included)

This hand operated press designed for use with Mitutoyo indicators, will allow you to insert crystals into bezels on test indicators, dial calipers and dial indicators up to 2-1/4" diameter. Comes with 8 different inserts as shown above. It can also be used for other brands of indicators including Interapid, Compac and Starrett. It is not suitable for Bestest indicators, Brown & Sharpe calipers or Federal dial indicators. Make sure that this press will work for the gages you have by reading the instructions printed below.

  • Crystal press order no. 7000 .... $246.00 order now (2014 price)
  • Crystal press order no. 7000 .... $199.00 order now (floor model, special price)

Glue or cement is never used to hold the crystal in place. Some manufacturers may use a thin bead of silicon to create a waterproof seal. This is a tricky maneuver and should only be attempted with caution.

While home-made presses can be improvised, for frequent use and reliable results we suggest ordering the portable Crystal Press #7000 shown above. It allows for easy crystal replacement on all size test indicators and AGD series 1 and 2 dial indicators (Federal indicators excepted), and certain dial calipers.

 

Why didn't we think of this before?

It may be easier to just buy a new bezel with a crystal already installed. If you don't have a crystal press, it's the way to go. Tell us what you need and we should be able to provide it. (Check our online parts lists for ordering numbers.) On the other hand, you can send us the indicator or calipers along with a check for $37 and we'll install the crystal (as long as the bezel or indicator isn't otherwise damaged, and as long as we're not dealing with a specialty crystal such as Intertest). Return shipping is included in the price. Click here to print a packing list to make it easy.

By the way, we'll replace test indicator crystals free of charge if you bought the (Swiss) indicator from us. Your new Swiss test indicator (Interapid, Compac, Bestest, Tesatast, Mercer) will have come with a coupon good for one free crystal replacement. Check this website for details.

 

Crystal Ordering Chart

 

Even though the manufacturer's name may be listed next to a particular crystal in the ordering chart below, it does not mean that every indicator or caliper made by that manufacturer can use that crystal. Be sure to read the instructions on this page before ordering. Wrong sizes ordered can only be returned for exchange.

These are not the manufacturer's original crystals. They are high quality replacements made in USA. If you need the original items, be sure to check the parts lists on page 72 for availability.

A discount of 20% applies when you order 3 or more of the same size crystal. Click on the linked crystal number to place an order.

Crystal No.

Diameter*

Flat plastic crystals with beveled edges (unless noted otherwise)

Price each

195

25.1 mm

Alina, Compac

$4.95

200

25.4 mm

Starrett 711-T1, Alina 88 (see notes)

$4.95

210

26.0 mm

Testmaster

$4.95

220

26.7 mm

Standard Gage, Mitutoyo

$4.95

240

27.9 mm

Bestest, Girod, Puppitast, TesaTast

$4.95

250

28.6 mm

MarTest, China, Interapid, Federal "A", B&S Group O

$4.95

29.0 mm

Starrett 80 series

285

30.8 mm

Mitutoyo "Pocket"

$5.95

345

34.7 mm

Mitutoyo, Teclock

$5.95

355

Kanon

$5.95

355-032

35.2 mm

Compac (.032" thickness)

$5.95

360-032

35.7 mm

Brown & Sharpe (.032" thickness)

$5.95

375

36.6 mm

Starrett model 196, Interapid

$5.95

380

36.8 mm

Starrett

$5.95

5.2109

37.3 mm

Kafer (without beveled edge, lies flat)

$5.95

395

37.8 mm

Bestest, Fowler-Verdict, Girod, TesaTast, Mitutoyo, B&S, Starrett

$5.95

415

39.0 mm

Alina, Puppitast, MarTest, Compac, Boice

$6.95

430

40.0 mm

Starrett, Ames

$6.95

460

42.0 mm

Mitutoyo

$6.95

480

China

$7.95

485

43.6 mm

China

$7.95

520

Peacock

$8.95

530

Teclock

$8.95

600

50.8 mm

China

$8.95

620

52.1 mm

Peacock, Intertest

$8.95

640

53.2 mm

Boice, Starrett, Mahr-Federal

$8.95

645

53.8 mm

Ames, CDI, Mitutoyo, S-T, Standard, Starrett, Teclock

$8.95

5.2101

53.85 mm

Kafer (these are flat plastic crystals of 1.1 mm thickness)

$8.95

660

54.65 mm

China, Dorsey, Teclock, Brencor, Brown & Sharpe

$8.95

675

55.5 mm

John Bull

$10.95

835

65.8 mm

Federal "D" (Federal part # CY-479)

$12.95

840

66.0 mm

CDI, Starrett

$12.95

940

72.4 mm

Mitutoyo AGD 3 old style (discount does not apply)

$16.95

1065

Compac, Tesa (discount does not apply)

$16.95

47084

Dorsey (discount does not apply)

$16.95

S035691

Teclock (discount does not apply)

$16.95

* note: this is the maximum diameter (0.1 mm) of the plastic crystal when flat. After the crystal is installed, it will be domed. If you measure an old crystal, which is already domed, take this into consideration. There are no refunds or exchanges on any crystals ordered in error.



 

How to replace a test indicator crystal

 

We list the indicators here by their manufacturers' names. Many indicators are sold with vanity names, so you may have to find out who the real manufacturer is. Order the appropriate sizes from the list above.

Alina: loosen, but don't remove, the three tiny screws under the bezel which can now be pried off, with your hands, like the lid of a take-away coffee cup. You may have to twist and turn the bezel a bit until it works. They can occasionally be stubborn. You'll need a press to insert crystal #195 (small) or #415 (large).

Alina 88: A thin blade knife will allow you to pry off the upper ring of the bezel. Be careful! This is an easy way to cut yourself. Original crystals are no longer available but the replacement crystal (#200) can then be inserted, without tools, before you press the ring back on. It is not necessary to remove the entire bezel.

Bestest (current models): the old crystals are removed with a simple tool that acts like a suction cup. You can improvise other methods but you're likely to cause damage. If the bezel is still round and in very good condition, you can probably just press the new crystal in place using your thumbs. If the bezel is dented or bent out of shape, then it's best to leave this to someone with the right tools. See online parts list.

Bestest (old models): the bezel can be pried off with a flat bladed screw driver. A metal spacing ring is removed from behind and the old crystal is pushed out with your thumb. Careful you don't cut yourself on the metal bezel. The new crystal is pushed in from below, again with your thumb. It is slightly over sized so that it will become convex in the process. The metal retainer is also put back in and the bezel is pressed back in place on the indicator. Use crystal #395 (for the large bezel) and #240 (for the small 28mm bezel). The much smaller 25 mm bezel, rarely seen, uses a crystal which we no longer carry.

Brown & Sharpe / Bestest briefly had its name on what is an Interapid Swiss-made indicator. See instructions for Interapid.

  • Brown & Sharpe 7028-4 uses crystal #375

Compac: remove the spring which is visible in the groove on the underside of the bezel. Use a thin needle to get the spring out. Try not to bend this spring out of shape. The bezel, if undamaged, lifts off easily. There is no need to remove anything else. You'll need to use a crystal press to get the new crystal into the bezel. Swiss crystals are brittle. If you apply too much pressure with the press, they'll shatter. When assembling make sure the tab on the outer dial fits into the space allotted for it on the inside of the bezel. If the bezel now turns too easily or too hard you can make adjustments by reshaping the spring. See the online parts list.

  • Important note: do not attempt to remove the bezels on the Compac 240 series test indicator (which has one revolution). Doing so, will result in the loss of hair spring tension. Unless you know what you are doing, send these to a repair shop for servicing.

Federal Testmaster: The old style Testmaster indicator has a bezel which can be tricky to remove. A slot on the side of the bezel will allow you to depress the spring which holds the bezel in place. Rotate the bezel until the spring is visible and then use a thin bladed screw driver to press the spring. If you can't get this to work and resort to prying the bezel off, you will inflict some damage on the top plate. The small bezel (about 1" diameter) takes crystal #210 which must be inserted with a press.

Fowler-Verdict old style indicators made in England use crystal #395 on the approx. 1.5" diameter bezel which need to be inserted with a press. The bezel can be pried off with a screw driver. The smaller one-inch diameter bezels are also pried off and Starrett Last Word indicator crystals (PT07112) can be pressed in place, although not always easily. It may not be necessary to remove the bezel since the new crystal could be pressed in place from above.

Gem test indicator: very much like the Starrett Last Word, the bezel is pried off with a screw driver. You can discard the wire ring and install the Starrett Last Word crystal. These crystals are molded to shape so you won't be able to use any of the flat crystals listed on this page. Refer to the Starrett parts shown on page 73.

Girod: the thin-walled bezel can be carefully pried off with a screwdriver. The new crystal #395 (for the large bezel) and #240 (for 28mm bezel) can be pressed into the bezel from below using your thumbs. Don't forget to put the spacing ring back before pressing the bezel onto the body.

Interapid: the bezel is threaded and unscrews. Hold the lower bezel plate steady with a small screw driver placed in one of the two holes while you unscrew the bezel. See online parts list.

  • Interapid 312B-3 uses crystal #375 (crystal press required)
  • Interapid 312B-2V uses crystal #250 (crystal press required)

Kafer: once you (carefully) pry off the retaining ring on top, the crystal just drops out. Replace it and you're set to go.

Mahr: Puppitast has a thin-walled bezel which can be pried off with a screwdriver, but do this carefully. The new crystal #240 (for the small faced models) can be pressed into the bezel from below. No special equipment is needed. Remember to put the spacing ring back into place before pressing the bezel back onto the indicator. The larger diameter bezels (about 1-5/8 inch) behave the same way and require crystal #415.

  • Puppitast 800 SM uses crystal #415

The oldest model Puppitast lift off the same way but they do not have a spacing ring and you will need a crystal press to insert crystal #415 into the 40 mm diameter bezels.

Mahr-Federal new style indicators "MarTest" have bezels which ride on a rubber o-ring. They can be pried off but you'll need a press to insert crystal #415 into the 1.5" diameter bezel. The smaller 30 mm bezel will take crystal #250.

Mitutoyo: newer models have plastic bezel & crystal combinations which snap on and off. Older models have bezels which can be pried off with a small screw driver. For the new series 513-412 and similar models (the combination black plastic bezel and crystal) you may also have to replace the rubber o-ring if the old one has stretched out of shape. The fit should be snug. Some Quick-Set and "Pocket" models still have metal bezels and a crystal press will be required to insert the crystal. See page 162 for a complete parts list.

  • 513-462 and 513-463 uses crystal #220 (crystal press required)
  • 513-518 and other "Pocket" style indicators use crystal #285 (crystal press required)

Peacock: (Pic Test) a wire spring holds the 34 mm diameter bezel in place. Three very small screws hold the 47 mm bezel in place. Don't lose these screws! For the 47 mm bezel, use crystal #520 which requires a press for insertion.

SPI: some of these models are made in China. Usually, when there is no country of origin printed on the dial, it's Chinese. For the new Interapid look-alike beginning with the number 14, you will be able to pry off the bezel with a screw driver and, after removing the metal spacing ring, you can press the new crystal in place from behind, using your thumb. Crystal #375 will do the trick. If the SPI indicator is made in Japan, then you'll want to refer to Teclock below. If it is made in Switzerland, then you'll want to see Compac above. If you're not sure, just send us the indicator with "replace crystal only" instructions.

Starrett Last Word: remove the chrome bezel by prying it off with a screw driver and insert the crystal from below (part PT07112) into the bezel. The crystal fits easily without resorting to a press or any other equipment. If your indicator still has a wire spacer, throw the wire away. The new crystals don't need this spacer. A pair of jeweler's pliers will help you squeeze the bezel back into place. This part can be ordered from the list shown on page 73.The discontinued model 711-T1 uses crystal #200 but this will have to be inserted with a press.

Starrett: the bezels for new models 708 and 709 series are held on by an o-ring. Use a screwdriver to wedge the bezel off. You'll need a crystal press to insert crystal #380. Snap the bezel back on. (The original Starrett part number is PT19043).

Teclock: assuming the dial diameter on this test indicator is about 1-3/8" then you'll want crystal #S035691. You'll find a retaining spring on the underside of the bezel which has to pried out with a pointy tool. When the bezel is off, you can pop out the old crystal using your thumbs (careful you don't cut yourself). The new crystal can be pressed in place with your fingers if the bezel is still round and in good condition. Otherwise, a crystal press will help insert it. Flat crystal #345 will also work but requires a press for certain.

Tesatast: (old models without model numbers) the thin-walled bezel can be carefully pried off with a screwdriver. The new crystal #395 (for the large bezel) and #240 (for 28mm bezel) can be pressed into the bezel from below using your thumbs. Don't forget to put the spacing ring back before pressing the bezel onto the body. For new models, see Bestest above.

 

How to replace a dial caliper crystal

 

Order the appropriate sizes from the list above.

B&S (Tesa and Etalon current models): the old crystals are removed with a simple tool that acts like a suction cup. You can improvise other methods but you're likely to cause damage. If the bezel is still round and in very good condition, you can probably just press the new crystal in place using your thumbs. If the bezel is dented or bent out of shape, then it's best to leave this to someone with the right tools. See online parts list. Old model 579-1 calipers have a bezel that pries off. You can easily insert crystal #395 into the bezel from below. Don't forget the spacing ring before you press the bezel back onto the calipers. (Very old model 578 calipers made in Germany use a 30 mm diameter crystal which we do not carry.)

Kanon: we do not have the original pre-domed crystals for the 6" calipers, but you can insert flat crystal #355 with a crystal press.

Mitutoyo: crystal #395 is flat, slightly over-sized (37.8 mm in diameter) and becomes domed when you press it in place. Crystal #345 is flat, slightly over-sized (34.8 mm in diameter) and also becomes domed when you press it in place. For 12" model 505-628-50 use crystal #460. Measure the diameter of the bezel to determine which crystal to use, or include the Mitutoyo model number when ordering. You will also find crystal and bezel assemblies at our online parts list. Buying the assembly eliminates the need for a crystal press.

Mitutoyo old model dial calipers You can use crystal #345 for the oldest model Mitutoyo dial calipers, the ones that do not have any model numbers printed on the dial face and the outside diameter of the bezel is 36.1 mm. You will have to insert the crystal with a press because it will be slightly oversized.Pry the bezel off carefully because it is thin walled and remember to remove the bezel clamp first. If you leave the bezel clamp on, you will most likely break it. These clamps are no longer available.

SPI and other made in China calipers. If the bezel pries off and there's a plastic spacing ring underneath the old crystal, and the inner diameter of the bezel, measured from below, is 42.5 mm then proceed as follows: remove the spacing ring and press out the old crystal by hand. Be aware that you may cut your thumbs doing this. You can then install crystal #480 by pressing it into place, from below, so that it becomes slightly convex. Replace the spacing ring and press the bezel back onto the calipers. If your caliper does not fit this description, we can't help you.

Starrett model 120-6 and 120A-6 calipers: since you'll need a press to insert the crystal, you may be better off ordering the bezel and crystal assembly instead. This way there's "no assembly required." The new bezels are held in place with an o-ring so you'll have to pry off the bezel, slowly, with something like a large blade screwdriver. Order crystal #380 or see online parts list. Model 1202 calipers (made in China) technically do not have replacement crystals available from Starrett, but you can use #395. Pry off the bezel with a large blade screwdriver (after removing the bezel lock screw). The old crystal comes out easily, but you will have to force the new crystal in place, with your thumb, so that it becomes domed. Don't forget the white spacer when you press the bezel back onto the calipers.

Tesa dial calipers are very similar, if not identical to the Brown & Sharpe dial calipers (see above). For the oldest, without identifying model numbers "Swiss Made Shockproof" you will need to pry off the bezel with a flat blade screwdriver. Crystal #395 (37.8 mm diameter) presses into place quite easily from below, just using your thumbs. Don't forget the faceted spacing ring before you press the bezel back in place.

 

How to replace a dial indicator crystal

 

Order the appropriate sizes from the list above.

Aerospace: these cheap made-in-China indicators aren't worth fixing, but you can replace the crystal, if you can get hold of one. The thin bezel pries off with a screw driver (put the whole indicator in a vise so you can get leverage) and no tools are required to put a new flat crystal in place. We do not carry these crystals.

Ames: a split retaining ring holds the old-style bezel in place. Carefully pry it out and the bezel will lift off. The new crystal is pressed in place from below with considerable force and it's not unlikely that the crystal will be damaged in the process. Use extreme caution. For Series 200 models order crystal #645.

  • Back plunger model 22A uses crystal #430 which is inserted with a press.

Boice (discontinued) bezels are held on with a wire spring. You can pry the bezel off with a large blade screw driver. You'll need a crystal press to insert crystal #640 on the large bezels and #415 on the small bezels.

Brencor uses inexpensive Chinese indicators on their chamfer gages. Remove the back cover and you will see a small tab held in place with a screw. Do not remove the screw but loosen it enough to slide the tab inwards, thus releasing the bezel. There is a spring on the opposite side. Be careful you don't lose this. Crystal #660 needs to be inserted with a press. Reverse the procedure to reassemble.

Brown & Sharpe (made in Switzerland): most of these new models have unit bezels and the crystal has to be pried out. Use your ingenuity but be careful not to damage the dial or bend the hand. We don't yet know how best to insert a new crystal nor what the proper sizes are. They snap in place like the Bestest indicators and one assumes that a similar inserting mechanism is used by the manufacturer. Since these gages are inexpensive, in the realm of things, they're considered "throw-aways" by the manufacturer and were not designed for easy servicing.The Group O dial indicators (MW 71 for example) use crystal #250 and will require a press for insertion.

Brown & Sharpe (made in USA): for the Group 2 indicators which had fiberglass bodies, such as model 599-8241-942, the bezel is held in place with 3 very evident screws. The crystal (#660) needs to be inserted with a press.

CDI: the 2-1/4" diameter bezel can be pried off—it rides on a plastic o-ring. Crystal #645 is inserted with a crystal press. Getting the bezel back on can be a task. It's a tight fit over the o-ring. Make sure the small tab on the inside of the bezel fits into the slot on the dial. Group 3 indicators with 2-3/4" diameter bezels have 3 screws in the side of the bezel which need to be taken out. Don't lose these! You can insert #840 crystal with a press.

China: The approx. 2-1/4" bezels take crystal #660. Remove the back cover and you'll notice a screw which holds a small sliding tab in position. Loosen this screw just enough to slide the tab back. The bezel will now lift off by pivoting it. Be careful not to lose the small wire spring which is also used to hold the bezel. The crystals we provide are flat and require a crystal press for insertion.

Compac Among the several different bezel styles, the large 82 mm diameter bezel unscrews and a new crystal (#1065) is pressed in place. Inserting these large crystals can be problematic. A press is mandatory. For the IAP365A dial bore gage, use 355-032 which is extra thin. A press is also required.

Dorsey: AGD 2 indicators have two springs holding the bezel in place. Remove the back cover and pull the springs back. The bezel will lift off, one side at a time. Be careful you don't lose the springs. Crystal #660 needs to be inserted with a press. AGD 4 indicators use crystal #47084 which, being oversized, needs a press for insertion and the edge of the crystal may benefit from a little bit of scraping to reduce the diameter. If the crystal lies flat (without a dome) however, it will touch the pointer (which is very delicate). Proceed with utmost caution. 3 hex screws hold the bezel in place.

Federal: three small screws in the side of the bezel hold it in place. Don't lose the screws because they are mighty expensive to replace. The newest Federal models have an o-ring. You simply pry the bezel off with the blade of a screw driver. The small Size A bezels have a small slot and you are supposed to be able to depress the bezel spring which you are supposed to see through the slot. Use a very small screwdriver and watch your fingers (danger alert). Large diameter crystals (D,E) may not work with standard crystal presses. For Federal crystals, see page 191.

  • Federal A1/2Q uses crystal #250 (crystal press required)
  • Federal B2I uses crystal #430 (crystal press required)
  • Federal B3Q uses crystal #430 (crystal press required)
  • Federal "D" indicators use crystal #835 (special fixture required for insertion)

John Bull: these old AGD 2 models have 4 screws clearly visible on the underside of the bezel rim. When removed, the bezel lifts off easily. Install crystal #675 with a press. Line up the tab on the outer dial ring with the slot in the bezel when assembling.

Kafer: the two tolerance marker rings have to be pried out on the AGD 2 dial indicators. Be careful, if the bezel is plastic you will probably damage it. The crystal can easily be removed and replaced without any tools. For plastic crystal order Kafer #52101 and glass crystal order Kafer #52102. See online parts list.

Mahr-Federal: The newest style indicator has a plastic bezel which pries off like the lid on a coffee cup. You can use a large flat-bladed screw driver to help. You'll notice there's no o-ring but a raised ridge inside the bezel which snaps into the groove on the indicator's body. There may be tolerance markers which can easily be removed if you grab the tabs with jeweler's pliers and pull inwards, towards the center of the bezel. The old crystal snaps out with a bit of force. The new crystal #640 is inserted with a press, again using considerable force because of the deep recess of the groove. You may be better off just buying a new bezel and crystal assembly in this case. See our parts list on page 72 for availability.

Mitutoyo: the newest models have the letter "S" attached such as 2416S. These have a single unit plastic bezel and crystal which snap on over a rubber o-ring. The crystal may pop out leading you to believe that it's replaceable. It isn't; but, if you're very careful, you can attempt to glue it back in place although we don't recommend this. See Mitutoyo parts lists for ordering numbers.

Mitutoyo: (old models) Getting the bezel off is one of the tricks you need to master. Remove the indicator back and you will see a bent piece of spring wire at one edge. This wire rides in the bezel's groove. You will need to depress this wire to disengage it. At that time, the bezel will lift up revealing another, smaller, similar wire on the other side. These have a habit of getting lost in the process, so be careful. The oldest models had a flat crystal which needs to be inserted with a press so that it becomes domed.

  • The AGD 2 indicators (they have a bezel diameter of about 2-1/4 inches) use crystal #645.
  • Crystals for the old AGD 3 indicators, use crystal #940.The Mitutoyo crystal press shown at the top of this page will not be suitable for AGD 3 indicators. The crystal diameters are too large for this press. We suggest having these professionally installed.

Peacock: we don't know enough about every Peacock model, but #1364 indicator with a 2-1/4" OD bezel will take crystal #620. This is not the original manufacturer's crystal, but it'll do in a pinch. It's flat and needs a press for insertion. After insertion it will be slightly domed. Remove the 3 small screws on the side of the bezel (don't lose them - we don't have these parts) and carefully lift the bezel off it's o-ring. The inner dial is more or less permanently staked to the bezel. It will lift off also and could damage the large hand if you don't watch out.

Scherr-Tumico (S-T): Some of the bezels have a large hole on the side. You'll find 3 screw heads by rotating the hole. Unscrew all of these and don't lose them! (We don't have these parts.) Crystal #645 can be inserted with a crystal press.

SPI: most SPI dial indicators are made in China. See instructions under "China" above.

Standard (Poughkeepsie models only): The newer, but discontinued style AGD2 indicators with ~2-1/4" bezel diameters and two small screws holding the inner dial in place will take crystal #645. These bezels are held in place with a nylon o-ring. Use a large bladed screwdriver to pry the bezel off. A crystal press is needed to insert the crystal. It may be hard to get the bezel to snap back onto the o-ring. Press down firmly and squarely with the palm of your hand.

The long obsolete D7-20045-B dial indicator for the small Standard bore gage uses crystal #220. This is a Federal indicator and instructions for Federal test indicators apply. You will need a crystal press.

Starrett: the old style size 2 dial indicators have a small hole on the side of the bezel. You're supposed to be able to depress the bezel spring, which holds the bezel on, through this hole using a small pin. Crystals will need to be inserted with a crystal press. Good luck to you. If you get it just right it'll work.

  • The new style AGD 2 size bezel series 25 snaps on and off. To get it off you'll want to press on one of the three plastic tabs you'll see underneath the bezel. Crystal #640 or #645 will need to be inserted with a crystal press. Either size will fit, but 645 will give a higher dome.
  • For indicator series 80 (the miniature dial indicator) the bezel can be pried off with a screw driver; If the wire retaining ring becomes distorted in the process, bend it back into shape. You'll need a press to install the new crystal. See parts list.
  • Series 81 uses crystal #430
  • Series 641 uses crystal #430
  • Series 655 uses crystal #840
  • Series 656 uses PT06908 available on page 32
  • Series 689 uses crystal #430
  • Back-plunger model 196 uses crystal #375. Replacement is similar to the Last Word test indicator (see above).
  • Starrett 25-631 uses crystal #640 (crystal press required)

The oldest Starrett dial indicators, probably 1950's and earlier, had three screws on the side of the bezel. Remove these and don't lose them! The bezel lifts off but you will need a crystal press to insert the new crystal. When reassembling, make sure the small slots in the dial and the underlying spring, line up with the small tab inside the bezel.

  • Starrett 25-F1" uses crystal #640 (crystal press required)

Teclock: the blue bezel of Model AI-921N rides on an o-ring and it can be pried off. Flat crystal #645 needs to be installed with a crystal press. It may be hard to get the bezel to snap back onto the o-ring. Press down firmly and squarely with the palm of your hand. Newer versions of these indicators use crystal #660. If you need a new crystal for the Teclock indicator, send us the entire gage along with a check for $30 and we'll install the appropriate crystal for you (shipping included). That way you'll know you're getting the correct size.

 

Crystal insertion - miscellaneous

 

Intertest: (caliper gage) The oldest models have metal bezels and crystal #620 is inserted with a crystal press. You'll have to remove the bezel to do this. Remove the instrument's back and you'll see the clamping mechanism that holds the bezel in place. Use caution since a slip of the hand can easily damage the plastic gears.

The older model Intertest, many of which are still in circulation, have a single bezel-crystal combination of clear plastic. It would seem to be an easy thing to replace this item. The old crystal can be pried off with a large blade screwdriver. Since rotating the crystal should also cause the dial to rotate, you'll have to line up a plastic tab on the inside of the new crystal with the notch in the dial. In theory, the new crystal snaps back on. Press squarely down on the crystal until it's in place. In practice, this often requires a bit of finagling on your part, including slight modification of the crystal in some cases. If the Intertest crystal rides on 3 steel balls, then you'll probably have trouble rotating the dial. You may have to live with this. If it snaps over a plastic o-ring, the dial may buckle or the whole thing barely fits. Occasionally, several small plastic tabs on the inside of the crystal may have to be filed away for a better fit. These crystals aren't cheap, so use caution. See Intertest for ordering information.

Truarc Waldes Kohinoor was a vanity dial on the oldest models of Intertest. (See instructions above)

Teclock: (pocket thickness gage) Remove the cover plate held on with a single screw. Lift the adhesive back and loosen—but don't remove—the two exposed screws. The tabs under the screws slide back so that the bezel will lift off. Crystal #530 can be inserted with a press.

Mitutoyo 7308 pocket thickness gage, old style: the pretty chrome bezel lifts off rather easily with the aid of a flat bladed screw driver. The 42.0 mm diameter crystal can be inserted using a crystal press. When slipping the bezel back in place, note that the "cut out" on the underside of the bezel has to be positioned in the upper left corner of the dial, so that it can clear the lifting mechanism underneath. You will see it, just pay attention. On newer models (they will have the letter N enclosed in a small circle) you will have to loosen a screw which can be accessed by removing the round label on the back of the gage. The label is glued in place. Use a razor blade and some solvent for this process and attmept not to cut yourself. Do not unscrew completely, just loosen! Then you will have to push back the brass clip which you see underneath the screw. This disengages the bezel wich can now be lifted off as outlined above. You will probably get a few grey hairs in the process.

Correx Gram Force Gage: assuming that the body hasn't been bent out of shape, the crystal falls out easily once you remove the retaining spring from above. New crystals with the maximum pointer assembly are available for easy replacement. Before installing the new unit, test the maximum pointer. It shouldn't move on its own, yet it should have almost no friction. The small screw can be used to make adjustments. (Word of caution: don't disassemble.) Also, check that the maximum pointer does not touch the dial when you reassemble. Bend it a little bit if necessary. See Correx information on page 10.

 

Is there a problem?

Q: I still can't figure this crystal press out. You wouldn't happen to have pictures or a video to show how it works? I can't believe the manufacturer didn't create instructions for this.

A: We install indicator crystals by the dozens each day and find it hard to believe that there is any special skill involved. Never-the-less... Like any tool, the crystal press takes practice. Repairing is usually learned as an apprentice by going to the factory and taking their classes or by being lucky and having a father who teaches you what he knows. The crystal press is designed for use by repair shops and the assumption is that they already know how to use these. Can you find a repair shop nearby who might be able to demonstrate its use?

 

 

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This page's most recent revision: 15 JULY 2014
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