Mitutoyo 3" Dial Indicator Repair

crashtestdummy · Jan 11, 2011

I dropped my Mitutoyo 3426-10 3" travel dial indicator. It was in a case, but the .001 needle is bent and the other needle appears to be off. Is it possible for me to fix this? Long Island Indicator lists their repair at $137, and I only paid $30 for the indicator. How difficult is it to remove the bezel?

PeteM · Jan 11, 2011

Hopefully there's no damage inside in this "shockproof" movement.

The bezel removes by unscrewing the tiny screws around the straight knurled side. You'll be able to get at the .001 hand and gently try to bend it back. If the .100 hand is off you might be able to rotate it back - but I'd double check that it had truly moved or that the rack hadn't skipped a few teeth. The pullers clockmakers use to pull hands may be your friend if you need to remove the hands.

Chances are you can fix this without too much effort.

crashtestdummy · Jan 11, 2011

PeteM said:
Hopefully there's no damage inside in this "shockproof" movement.

The bezel removes by unscrewing the tiny screws around the straight knurled side. You'll be able to get at the .001 hand and gently try to bend it back. If the .100 hand is off you might be able to rotate it back - but I'd double check that it had truly moved or that the rack hadn't skipped a few teeth. The pullers clockmakers use to pull hands may be your friend if you need to remove the hands.

Chances are you can fix this without too much effort.

Thanks for the reply. There aren't any screws on the bezel, however it's a friction fit and I removed it. I straightened the large hand and it looks better.

It appears that there is binding somewhere. It compresses better than it returns. It binds somewhere. Also the large hand will spin freely on the return. Looks like it needs a visit to the indicator doctor.

Kansas · Jan 11, 2011

As stated you can repair the hands, fairly simply. I would not be surprised if there is some further damage. So would suggest checking the indicator with a set of gage blocks. For $30.00, why not replace it, and keep the other for parts or sell on e-bay?

PeteM · Jan 11, 2011

crashtestdummy said:
Thanks for the reply. There aren't any screws on the bezel, however it's a friction fit and I removed it. I straightened the large hand and it looks better.

It appears that there is binding somewhere. It compresses better than it returns. It binds somewhere. Also the large hand will spin freely on the return. Looks like it needs a visit to the indicator doctor.

Interesting about the screws. I have the same model indicator (with screws), but perhaps of an earlier vintage.

I'm guessing you don't want to spend the $$$ for a fix (?); so you might as well open this up and see if you can free things up. There have been previous threads on this topic. Looking for a skipped rack, how not to oil it, and so on. Worst case -- someone on Ebay might want the bezel cover for a repair.

Many folks use a long travel indicator like this to measure such things as travel on a lathe. For about the same money as the repair you could buy a cheap caliper-scale-type single axis DRO and readout.

Good luck.

crashtestdummy · Jan 11, 2011

PeteM said:
Many folks use a long travel indicator like this to measure such things as travel on a lathe. For about the same money as the repair you could buy a cheap caliper-scale-type single axis DRO and readout.

Good luck.

I originally bought this indicator of of Ebay. It had a crummy photo, so no one bid on it. Other than an engraved name on the side, it was brand new. I bought it to use on the lathe, but since then the Travadial has been repaired and is working.

I may look into having it repaired, although it may end up joining the 50 or more other indicators that I have and rarely use.

As for selling the bezel, that's just wrong. I hoard tools, I don't sell them.

Holescreek · Jan 11, 2011

I had a suspicion about the binding issue so I pulled up the exploded drawing for that model. True to form, there are 2 screws that hold the brass back plate to the cast body.

More than likely, the back plate took such a jar when it was dropped that it has just shifted position on the body and the gears aren't meshing properly.

The good news is it isn't terribly hard to fix. The bad new is that you have to remove the hands (without breaking the shafts) to take off the white aluminum face plate to access the 2 screws. Once you have access to the screws it should be just a matter of loosening the screws a tiny bit and repositioning the pinion against the rack.

Before you shift the backplate for adjustment put the big hand back on it's shaft (using finger pressure only) so you can hold it in position while you move the backplate into place. Otherwise if you get the rack and pinnion seperated too far you the main spring will unwind , loosing the preset tension.

It's not too bad of a repair, especially if you see it done once but for some reason people are shy about opening these things up. -Mike

BTW you can get a cheap hand puller on Ebay for around $5 IIRC.

crashtestdummy · Jan 12, 2011

Thanks Mike, great repair info as always. I've ordered a hand puller, so when it gets in I will attack the problem.

This is a photo of the inside. If I keep pressure on the right side of the shaft it will plunge and return freely. Without pressure it will plunge OK, but binds on the return.

tknick · Feb 9, 2011

Mitutoyo

I would agree with Kansas on this one. If a new one cost $30.00 go for it!! I think it possibly skipped a few teeth as well, which in turn takes patience.

Ted :willy_nilly:

crashtestdummy · Feb 9, 2011

tknick said:
I would agree with Kansas on this one. If a new one cost $30.00 go for it!! I think it possibly skipped a few teeth as well, which in turn takes patience.

Ted

The cheapest I can find a new one is $176.00.

I have had it apart and it still wants to skip a little on the .001 hand. I'm pretty sure that the rack is slightly bent.

VFP · Feb 9, 2011

crashtestdummy said:
The cheapest I can find a new one is $176.00.

I have had it apart and it still wants to skip a little on the .001 hand. I'm pretty sure that the rack is slightly bent.

Have you checked with Long Island Indicator. They do repairs on that type of equipment. 027 : Long Island Indicator Service : Sales, Repairs and Spare Parts

crashtestdummy · Feb 9, 2011

VFP said:
Have you checked with Long Island Indicator. They do repairs on that type of equipment. 027 : Long Island Indicator Service : Sales, Repairs and Spare Parts

Their rate for a 3" dial indicator is $137.00. Another repair service that I looked into charges 50% of the LIST price of the indicator.

Holescreek · Feb 9, 2011

Did you see any damage on the rack or the pinion gear?

If not, you possibly just lost the preset mainspring spring tension when the original incident occurred.

I'd bet that the mainspring pretension is gone, but if you saw a damaged rack or pinion it's not worth going into. Resetting the tension is no big deal, but I won't go through it unless you think the gears are good.

Damaged parts will look something like these:

Holescreek · Feb 9, 2011

I suppose there could be some damage since it fell hard enough to bend the hand, but just in case, here is how I go about pre-tensioning the mainspring.

1) Pull the bezel back off and remove the hands.
2) Remove the face and the 2 screws that hold the base plate on.
3) Pull the base plate (the works) from the housing.

4) Put the large hand back on it's shaft using finger pressure only.
5) Use a finger to rotate the large hand while watching the mainspring on the other side. Figure out which way you have to turn the hand to tighten the mainspring. (There is no standard direction for rotation).
6) Tighten the mainspring by rotating the hand 6-12 turns.
7) While holding the large hand so the mainspring doesn't unwind, place the works back into the housing and mesh the gears so the mainspring doesn't unwind.
8) Replace the screws.

9) Move the shaft up and down a few times and listen to the noise the gears make.
10) If they sound noisy, loosen the 2 screws and shift the works slightly by rotating them to adjust gear mesh.
11) Once they sound good, tighten the screws.
12) pull the hand back off and replace the face.
13) Reinstall the hands in the proper position.
14) Test.

crashtestdummy · Feb 10, 2011

Thanks Holescreek,
The long story is;
I bought a puller.
I pulled off the hands.
I removed the face.
I readjusted the mechanism with the 3 screws under the face.
I went to put it back together and couldn't easily get the small hand back on.
I took it to a local clock repair guy at the jewelry store to get the hands put on.
The repair guy had it for a couple of weeks and it got the hands back on, but couldn't make it so it wouldn't skip. Since he couldn't get it to work right, there was no charge.

The small hands seems to be working fine. The large hand (thousandths) jumps around and doesn't move in the same linear rate as the plunger. It almost acts like it is slightly loose on the shaft.

I may revisit it one of these days, but it's difficult to find uninterrupted time.

strom19 · Aug 16, 2012

{troll text deleted - trl}

crashtestdummy · Aug 16, 2012

strom19 said:
{troll text deleted - trl}!

I still haven't repaired my 3" Mitutoyo. I did recently buy a new bezel and crystal from Long Island Indicator for an Interapid DTI. I paid by credit card, but i don't remember if it was over the phone or on their web site. I know I didn't fax them a copy of my card.

The new part wouldn't thread onto my indicator. I contacted Long Island Indicator by email, got a response and returned the part. They were a little slow getting out a replacement, but I did get one and it was relatively painless. YMMV.

strom19 · Aug 17, 2012

Well you were fortunate. I have never seen any company do business like Long Island
Indicator Inc. I would never deal with them again.....

strom19 · Aug 17, 2012

Some people just can't stand the truth....Such as this real Leigh guy. I'll bet he's a Democrat for sure!

precrepair · Aug 21, 2012

{spam text deleted. Such correspondence should be conducted via PM. - trl}

The policy on spam posts is clearly stated here: http://www.practicalmachinist.com/v...copyrighted-material-spam-241690/#post1758513

Mitutoyo 3" Dial Indicator Repair

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