DTI Bezel/glass removal

[Dr_GMJNParticipant @dr_gmjn]

All, Does anyone know how to remove the glass/bezel from this DTI?

The needle is bent and I’d like to straighten it if possible.

Thanks.

[Grindstone CowboyParticipant @grindstonecowboy]

My Verdict one just pulled straight off – a bit daunting, but try gently levering it with something softish so as not to mark the case.

Rob

[MikeKParticipant @mikek40713]

It should pull, or pry off.  But only the knurled part.  That is, only pry at the very edge, NOT under the full width of the ring.

See the image of my dial indicator.  The DTI is similar.

https://www.model-engineer.co.uk/forums/topic/dial-indicator-disassembly/#post-727140

[HopperParticipant @hopper]

THE INDICATOR BIBLE

[Hopper]

On Hopper Said:

THE INDICATOR BIBLE

Mine’s re-branded Kennedy, which isn’t on the list. No idea who made it.

I noticed that looking from the back, the outer silver ring moves round with the bezel, so assuming the bezel is fixed to that, there’s no way it’s coming off.

I tried prying the bevel off, but it’s clear that much more force would result in damage.

Removed the side plate to see if that revealed any securing method, but only a couple of screws holding the face on (which I assume in turn traps the outer ring in place).

So…I’m stumped. I assume that the bezel is assembled first, then the glass (plastic) is pressed into the bezel. So I need to pull the glass out of the bezel. I wonder if hot glue on a stick would do it? how difficult is it to replace the glass – does it need a special jig?

[MikeK]

On MikeK Said:

It should pull, or pry off.  But only the knurled part.  That is, only pry at the very edge, NOT under the full width of the ring.

 

DIY pulling and levering is high-risk in my experience, because the bezel tends to twist and jamb.   Watch repairers use a tool deisgned to apply pressure evenly around the circumference, this example sold by Walmart in the USA.  No idea how well it works!

Watchmakers use another tool to replace the bezel and crystal.   It’s a sort of padded press adjustable to grip the watch diameter, and then pushes the bezel/crystal evenly into position.

My limited experience suggests removal/replacement varies enormously from easily done by hand with extemporised tools, to so tight that proper tools are essential.  Bezels and crystals fitted to cheaper products may be loose and easy compared with better made equivalents.

Anyone with high standards should question the value of straightening the needle.  That poor DTI has been whacked hard enough to bend the needle.   Might have damaged teeth and bearings, such that the instrument sticks and doesn’t track smoothly over the full range and the calibration is out.   Before mending the needle, I’d carefully check the DTI is still functioning properly, i.e. no symptoms whatever of internal damage.

Dave

 

 

[Dr_GMJNParticipant @dr_gmjn]

Thanks Dave. I admit that sometimes as a relative newcomer to model engineering, I’ve done daft things that have resulted in “non-optimal” situations with various tools!

I think in this case it must have been an acceleration of the needle that possibly casued it to bend.

It appears to work fine and is still smooth.

[Michael GilliganParticipant @michaelgilligan61133]

See p619 here:

https://www.newpages.com.my/customer/attachments/14498147054f8b2bdbc5a388c3f67554ec200eeedc.pdf

It would appear that suitable 32mm diameter ‘crystals’ are available … and by inference therefore, yours should be removable.

MichaelG.

[Michael Gilligan]

On Michael Gilligan Said:

See p619 here:

https://www.newpages.com.my/customer/attachments/14498147054f8b2bdbc5a388c3f67554ec200eeedc.pdf

It would appear that suitable 32mm diameter ‘crystals’ are available … and by inference therefore, yours should be removable.

MichaelG.

Thanks Michael. Yep, so I think it’s obvious now that the glass pops off the bezel. I just have to figure out how to do that. I don’t think I’ve got a valve grinding suction tool, but I’ll have a look.

[Dr_GMJNParticipant @dr_gmjn]

Mission accomplished.

I found an old arrow with a sucker on the end. The sucker wasn’t strong enough to do anything, so I used hot melt glue to help it. Pulled straight off with no problem:

The glue took some removal with a blunt knife and some IPA, but cleaned up fine:

Straightened the needle as best I could (it’s angled down slightly towards the face I think), and re-fitted the plastic, which was pretty easy after working it back into the bezel by rolling and working it against the kitchen table:

Much better. Not an essential job, but it makes it nicer to use. Thanks all.

[Michael GilliganParticipant @michaelgilligan61133]

Well done, Sir !

MichaelG.

[MikeKParticipant @mikek40713]

Yep, I’m glad my faulty advice wasn’t listened to.  It’s good that you got your needle straightened again.

Mike

 

[MikeK]

On MikeK Said:

Yep, I’m glad my faulty advice wasn’t listened to.  It’s good that you got your needle straightened again.

Mike

 

Thanks Mike. To be fair, there was no reason to think the outer knurled bezel wasn’t separate to, and pressed onto, the ring. No way of knowing until I tried to pry it off, but it was pretty obvious it wasn’t going to budge. All part of figuring it out.

[Author]

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