Gem DTI

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Mr Ron
Posts: 1582
Joined: Tue Dec 22, 2009 12:36 pm
Location: Vancleave, Mississippi

Gem DTI

Post by Mr Ron » Wed Jul 11, 2018 2:51 pm

I have a Gem DTI, model 222, an old one for sure. I need to use it now to assist my installation of my new DRO. The DTI is working erratically. The needle won't return to zero consistently in one direction, but it does in the other direction. I put a drop of light oil in the mechanism, but it didn't do any good; any thoughts?
Mr.Ron from South Mississippi

John Hasler
Posts: 868
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Gem DTI

Post by John Hasler » Wed Jul 11, 2018 3:11 pm

I have one of the those. Rinse all the oil out (I use starting fluid) and oil only the bearing where the probe pivots. Make sure the needle isn't dragging.

Mr Ron
Posts: 1582
Joined: Tue Dec 22, 2009 12:36 pm
Location: Vancleave, Mississippi

Re: Gem DTI

Post by Mr Ron » Thu Jul 12, 2018 4:19 pm

John Hasler wrote:
Wed Jul 11, 2018 3:11 pm
I have one of the those. Rinse all the oil out (I use starting fluid) and oil only the bearing where the probe pivots. Make sure the needle isn't dragging.
I'll give that a try. According to Long Island instrument repair, the Gem is not considered a good DTI and not worth repairing. They call it a poor copy of the Starrett "Last word" DTI's. I got it for free, so I'm not to concerned if it doesn't work as it should.
Mr.Ron from South Mississippi

John Hasler
Posts: 868
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Gem DTI

Post by John Hasler » Thu Jul 12, 2018 4:41 pm

I've got one of each. I don't see any significant difference.

Harold_V
Posts: 17014
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Gem DTI

Post by Harold_V » Fri Jul 13, 2018 1:58 am

John Hasler wrote:
Thu Jul 12, 2018 4:41 pm
I've got one of each. I don't see any significant difference.
If that's the case, my opinion of the Gem is not good. I've owned a Last Word since 1958. It was returned to Starrett for repair when it was not reliable, but it quickly returned to that same condition. The only real use it has now is in removing taper from a grinder, and it seems to deal with that adequately. There is no doubt in my mind, they are not a good indicator (keeping in mind, the vast majority of my instruments are Starrett).

The user has no idea they aren't working, as they behave as if they are, but when a more sensitive indicator is used in conjunction, the difference is obvious. Mine remained motionless when, in reality, I had something like a half thou movement. Doesn't sound like much, but the job I was running had only .0002" tolerance, so I was woefully out of tolerance when it indicated zero movement.

This topic has been discussed endlessly (without rancor). It is generally accepted that there are far better indicators on the market. My choice is the B&S BesTest, of which I own three. I have owned one of them in excess of 50 years. It already requires a replacement of the crystal, and has, otherwise, served me perfectly well without any issues. You just can't buy good things these days. :D

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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