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Thread: Dial indicator repair in Oz?
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29th Oct 2020, 08:14 PM #1Golden Member
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Dial indicator repair in Oz?
Hi all,
I have a wonderful collection of not quite working, or sticky, or not quite returning to zero precision indicators.
PXL_20201029_085439929.jpg
Id really like to make use of some, especially the mit 0.0001 dti.
Anybody recommend a repair service whose prices make sense?
Many thanks,
Greg.
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29th Oct 2020, 11:10 PM #2
Not in Australia but I think it's call long island, your postage would be saved since you have a few.
Other than that pull the backs off, clean and oil them yourself, there is a special oil that costs a bit, but is well worth it so I am told.Using Tapatalk
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29th Oct 2020, 11:21 PM #3
Get to know an old time watchmaker. Not one of these new fangled digital watch repair guys.
By definition that will make him old. One of these guys should be well capable of freeing up the mechanisms.
Grahame
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29th Oct 2020, 11:23 PM #4
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30th Oct 2020, 12:40 AM #5
Hi Greg,
Don't use oil on them ! It is probably oil vapour that has condensed on them and collected dirt.
I cleaned one of mine in an ultrasonic tank with just plain water and a spot, literally, of detergent. It worked OK to free the mechanism up. I used a hair dryer to get it dry, it took ages !Best Regards:
Baron J.
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30th Oct 2020, 07:36 AM #6Golden Member
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Dave/Grahame/Baron, thank you.
I have to say, I only distantly considered giving it as go myself - I gave one of the millis to a friend and he fixed it - but he's a lot braver than I am with such things. But, I watched a few vids last night and, indeed, looks like something one might be able to do if careful. There was also the sonic cleaner method shown. I have a small one of those.
With the 'get someone to repair it' thing, I figured I could likely sell one or two of them (being quality 0.001mm or 0.0001" units) and cover the cost of refurb of the others.
I'll gather up some courage and maybe give it a go this weekend. Wish me luck. If I learn anything I'll post back here.
Thanks again for the encouragement and advice.
Greg.
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30th Oct 2020, 09:29 AM #7Most Valued Member
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For the dial gauges. (I'm no expert but I have been inside a few)
Use no oil on the spindle, to the best of my knowledge they run dry.
To start with I wouldn't touch the insides.
The first thing I try is cleaning the spindle with isopropyl.
From my limited experience getting the spindle out varies from nearly impossible to impossible (ok its been a while since I was inside one so maybe that's overstating things, but it sure felt like it)
If possible put a few drops on the spindle from the inside, run it in and out a few times. wipe from the outside. repeat.
That improves most of them.
Remember the Federal and Newall have spindle bearings are both ends.
After that things can get tricky, at least none of them has a second hand.
You seem happy to give it a go so start with the Federal, if you screw that up I maybe able to replace it(except for the dial face)
The DTI's are pretty simple inside what is its fault?
Oil is a tricky subject with just about every oil in every price range backed by someone. About the one thing most agree on is "less is more"
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30th Oct 2020, 07:42 PM #8Golden Member
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I have done some cleaning and lubrication on all of my dial gauges (which improved them), except the Mahr Millimess which I have never been desperate enough to open.
The Millimess used to have a brisk but measured response, but is now (like its owner) lethargic unless warmed up by exercise, so the time to open it may be near.
I have used synthetic clock oil (E.490007 615 Synthetic Clock Oil - Clock Movement Importers) because it is more stable over time than refined mineral oils. However I am not sure if I have the most suitable viscosity for my more precise dial gauges. Possibly watch oil would be better, but at the time I bought oil (ages ago) the local suppliers seemed to be price gouging for Moebius oils and I was in a hurry to get a gauge working so chose the clock oil.
Also it helps to use watch oilers so you can apply a minute quantity of oil. As mentioned, too much oil can be bad news and a pain to clean up if it gets to places unwanted.
Bill
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30th Oct 2020, 07:55 PM #9Philomath in training
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There is not much to them
https://metalworkforums.com/f65/t187...t-apart-lately
I also have the Long Island Indicator book, so could have a look in there and see whether it says anything of relevance.
I was also taught that they should be dry.
Michael
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30th Oct 2020, 08:10 PM #10
Thanks for that, I have a few sticky indicators that I have dropped some light oil on years ago.
I had a good Starret one on my quill permanently mount on hydraulic arms for indicating, sadly I lost the knurled top as it vibrated loose, the last time I found it, but not this time.
So I replaced it with a cheap Chinese indicator which I should have done long before.
Now to either buy or make a new knurled knob after I work out the thread pitch, but no real hurry as I have other indicators and it's only cosmetic really.Using Tapatalk
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30th Oct 2020, 09:21 PM #11Diamond Member
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I just googled Dial Indicator Repair and found a number of Business in Australia doing repairs. The last couple of links seem to be calibration than repair, but I thought I would add them in anyway.
https://www.gawins.com.au/ Dial Gauges - Perth, Western Australia - Calwest Services https://www.pcsmeasure.com.au/services https://industrial-instruments.com.au/ https://www.zenithinstruments.com.au...ation-service/All The Best steran50 Stewart
The shortest way to do many things is to do only one thing at once.
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1st Nov 2020, 03:42 PM #12Member
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- Cairns, Qld.
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DTI Indicator Repair
As it happens, I have been working on my Mercer 1 inch x 0.001" dti these past couple of days. It had been getting sticky in operation & not returning to a reliable zero, varying up to 5 thou indicated at that point. Not much use at all really for a nice old UK-made instrument.
A first attempt inside with electronic-type cleaning spray & minimal oiling on the plain pivots didn't improve matters one bit.
Therefore I dismantled the unit down to the mechanism only, which was soaked & agitated in thinners for 15 minutes or so in a small clean container. A tiny amount of debris was evident afterwards. It definitely felt different in freedom of operation after that cleaning.
Inspection overall with a jewellers loupe showed a need to further clean foreign matter stuck in the teeth of the plunger rack. The plunger faces & end bushes were cleaned as well. An ultrasonic cleaner would have been good as an alternative.
After drying & re-assembly, & some fiddly experimentation with how much pre-load needed to be on the tensioning hair-spring of the final gear (The one that drives the small 100 thou. counter needle), operation was returned to normal.
A reliable zero & sensitive operation was confirmed when checked alongside a newer & known accurate gauge on a ground test piece in the lathe chuck. I have not lubricated the internal bearings thus far, but did use a drop or two of very light oil on the plunger bushes in the main body.
Mercer dti clean @ 40%.jpgMercer dti repair @ 40%.jpg
We'll see how it operates from here. Hopefully given it a new life....
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1st Nov 2020, 09:01 PM #13Golden Member
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Hello all
My knowledge on DTI's is limited only having pulled one apart. I did an apprenticeship in Aircraft Instrument over 30 yeas ago.
On the ones that I have seen they sort of can't go out of calibration. What I mean by this is that they are essentially a rack driving a fixed gear train. What causes errors is a thing called backlash. With no backlash you end up with play in the gear train which will give erratic readings.
On some there are two separate backlash devices. The first takes out backlash by applying a small force to try and wind the spindle down. It can be as simple as a small gear and hairspring,
The second is a bit more complex and not found in all DTI's. Its purpose in life is to provide what is often referred to as shockproof. How it works is if the plunger is moved quickly it winds up the hairspring to slow the movement of the pointer down. Think of it as a shock absorber in a gear train. If there is insufficient spring pressure or excessive friction in the gear train an error will occur. This error is not repeatable and vary every time. So what I meant is the calibration cannot be changed. The friction can be eliminated or the hairspring can be set.
Right , that is enough theory for now. If these were mine I would select the least favorite. I would pull the back of. Usually two screws. Nothing should fall out at this point. If something does the DTI is broken and not just dirty. I would then attempt to identify the two backlash devices. With a fine pointer I would give the gear train a "wobble" upstream of the backlash devices. If you can get any movement it is not that gear train causing it to lock. This generally leaves two remaining problems. Grit, corrosion or stickiness on the plunger shaft. For that i Would try flushing the shaft with a cleaning fluid of some sort. The second problem may be that most plunger shafts have a slot with a pin to stop rotation. This can wear or have grit buildup. Inspection will help here.
If you get this far you should have an idea of what is causing the fault. If you don't have to disturb the backlash gears and can clean the grit it would be the easiest solution.
Once you have mastered the first one, rinse and repeat until they are all working.
Steve
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2nd Nov 2020, 06:33 PM #14Senior Member
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If you get this far you should have an idea of what is causing the fault. If you don't have to disturb the backlash gears and can clean the grit it would be the easiest solution.
Thank you Steve.
Cheers
Roger
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3rd Nov 2020, 02:29 AM #15
Hi Greg, Guys,
Those anti backlash gears are a pig to set properly ! I've a Mercer that I've stripped and cleaned, I still can't get the backlash setting right. The hair spring is either not wound up enough or wound up too much ! The setting moves when you tighten the screws. Otherwise its OK.Best Regards:
Baron J.
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