Author Topic: Recommend prismatic type universal indicator stand  (Read 1818 times)

Online PekkaNF

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Recommend prismatic type universal indicator stand
« on: October 11, 2016, 03:12:00 AM »
I'm not sure what is the real name for an indicator stand that has an inverted V on the bottom and T-groove on the flat top.

Anyways, the item i mean looks like this:
http://blackhawkengineering.in/images/dial_indicator_stand.jpg

Where to get one:

1) Indicator stand that is reasonably accurate without major rebuild for normal workshop use.

2) Other one, least 250 mm long, ideally 350 mm long to cobble up some sort of bench centre:
http://www.hroberts-di.com/uploads/product/zoom_Mitutoyo_967-201-10_Bench_Centre.jpg

For #1 I have seen expressions like "universal indicator stand" used, but it will bring up all sorts of magnetic bases. I need one that is of reasonable quality, not too flimsy to bend under indicator load and stuff. It does not to be completely flat and parallel to micron accuracy. Just an heavier indicator stand. I don't mind paying a little extra.

For #2 something of similar than #1, but larger. The most important thing is of approximate shape and stability. I could buy chinese/indian eBay stuff for semifinished base and mill/grind the centre stands to fit. Or buy something like centre stand and finish it myself.

On this one real ones are way too big (one was sale here, but it was like 400 kg 300 old german one) which I have no space or very nice but not fit for my purse.

Outside TIR readings I can measure for cylindrical pieces, but taper and/or center pip/hole parts do not indicate well on surface plate/prisms.
http://madmodder.net/index.php/topic,11699.msg137759.html#msg137759
This that sort of application I'm heading. I'm getting a grinder little closer to usefull level and I need to measure How I am doing.


So here we go: Advises, rumours, gossips or even a hint where to look for are greatly appreciated.

Pekka

Offline Pete.

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Re: Recommend prismatic type universal indicator stand
« Reply #1 on: October 11, 2016, 12:11:53 PM »
That's a comparator stand. I have one made by Mercer but it has tee slots both sides rather than a vee.

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #2 on: October 11, 2016, 01:30:30 PM »
I always thought that comparot stand is completely differnet type of animal:
https://cdn.mscdirect.com/global/images/ProductImages/7512802I-21.jpg
http://i.ebayimg.com/00/s/OTYwWDEyODA=/z/sAMAAOSwLnBXVefF/$_1.JPG

When you need to compare bunch of stuff with a stack of slip gage.

Pekka


Offline chipenter

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Jeff

Offline Pete.

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Re: Recommend prismatic type universal indicator stand
« Reply #4 on: October 11, 2016, 02:25:18 PM »
I always thought that comparot stand is completely differnet type of animal:
https://cdn.mscdirect.com/global/images/ProductImages/7512802I-21.jpg
http://i.ebayimg.com/00/s/OTYwWDEyODA=/z/sAMAAOSwLnBXVefF/$_1.JPG

When you need to compare bunch of stuff with a stack of slip gage.

Pekka

Yeah that's what it does.
Look up Mercer 108. There's a few on ebay one is listed as a DTI stand and the guy has fitted the stops as feet but really they should go on top to rest the part against.

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #5 on: October 12, 2016, 06:47:04 AM »
I always thought that comparot stand is completely differnet type of animal:
https://cdn.mscdirect.com/global/images/ProductImages/7512802I-21.jpg
http://i.ebayimg.com/00/s/OTYwWDEyODA=/z/sAMAAOSwLnBXVefF/$_1.JPG

When you need to compare bunch of stuff with a stack of slip gage.

Pekka

Yeah that's what it does.
Look up Mercer 108. There's a few on ebay one is listed as a DTI stand and the guy has fitted the stops as feet but really they should go on top to rest the part against.

Thank you.

uuh. + Postage: 22.03 and not very clear of accuracy. Looks like dunked in acid bath to remove (slight?) rust, but could have filed or othervise fiddled with it to look better?

I have no idea why he calls it comparator stand.

Pekka

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #6 on: October 13, 2016, 05:44:32 AM »
These are not that common...specially the ones that have T-grooves at top and bottom, or least a prism.

This looks like a straight bottom:
http://www.machine-dro.co.uk/baty-bench-comparator-stand.html

I tried to find something semi fabricated... Looks like T-Slot table/profile is one option.

If slit 2-3 parts this could do whole lot of measurement kit:
http://vacuumtables.co.uk/product/steel-t-slot-plate-3020/

This would be even more versatile, because it has T-slot on both sides:
http://www.zappautomation.co.uk/pt-profiles-pt-50-t-slot-plate-w250-x-h20.html

My preference would be cast iron, but just wondering. How much those would warp if I slit them 2-3 parts? I would imagine that steel probably not much, but extruded aluminium would not like to stay straigt. Ali might be best left intact. It's not that heavy anyway.

Pekka

Offline Pete.

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Re: Recommend prismatic type universal indicator stand
« Reply #7 on: October 13, 2016, 10:03:36 AM »
It's a shame you weren't looking a month ago

http://r.ebay.com/MFdfBW

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #8 on: October 13, 2016, 11:04:45 AM »
Damnit!

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #9 on: November 04, 2016, 04:48:29 AM »
Ok. Bought few things and this one is part of the OP:
http://www.sometcz.com/en/store/the-others/dial-indicator-stand-t-bases

Got it this week and I have been using it:
+ As described, it is big and heavy
+ cast iron stand does not rock either way, it has a 0,01 mm dip on the middle both sides. Intentional?
+ ugly but works
+ No twist or bow. Grinding looks level. When spun on granite, feels about right.

Minor/expected faults:
- cast iron base has few cast pores and edges are rounded from front loader treatment, but definately cast has been naturally aged and then milled/ground later.
- column is not straight, the whole affair looks really crappy. It mounts tight, but is visibly tilted. Does not really matter to accuracy, but - really!
- indicator mount/adjustmet went straight to bin. Lucily standard M4 thread, mounted there back lug dial gauge.

With modifications it looks absolutelu appaling but works pretty well. Stark contrast to chinese which I left to shop (170!!!!!!!!!) which is pretty and painted, corners crisp and seems fine, but base had twist and rocked.

Pekka

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #10 on: December 24, 2016, 03:46:33 PM »
Funny part is that I complained about the orginal missing fine adjustment on the dial holder. They said they would send a new holder. They could not find a adjustement parts and finaly sent me a completely new stand.

I checked it and it looked fine, but because packing was only cardboard it had been dropped somewhere on the way to floor and pagaging had a hole in it.....

Because it is cast iron I used diamond file to file of the raised edge. Then I got a little enthusiastic and took a laping plate, abrassive and parafin oil. 15 mins of good fun and some cleaning/checking showed the base to be straight and level to better than 0,01 mm trougout the whole lenght of the base. Sorted.

Butthe old one is another matter. It is usable, but it's corners are a bit high, it has slight twist and step on paralelism of top to bottom surface. Gave it a bit more workout and it became better, but it is hard to correct with hand lapping.

Pekka

Offline Pete.

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Re: Recommend prismatic type universal indicator stand
« Reply #11 on: December 25, 2016, 05:30:09 AM »
If you handled it with bare hands then those readings after lapping could be just bending from heat.

What did you lap it with? Something coarse like fine valve grinding paste will remove scraping marks in minutes. Another thing is the pattern you use when lapping, if you don't describe large enough circles you might not keep an even thickness of slurry under the part and lap a hollow in the base. That said, for the use you're going to put it to, a slightly hollow base is far better than a crowned one.

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #12 on: December 25, 2016, 06:06:35 AM »
Thank you. All very true and good points. Let me explain a bit more what I was trying acieve by lapping wrong way.

That lapping plate is 350*250 two sided model it is prooven to be pretty straight.

I used coarse valve grinding paste, but first used other piece to break it down. I know it is not ideal, but this piece is not ideal either and it this bases were ground, not scraped. No precision instruments were harmed.

I'm normaly using large figure of eight in multiple direction on the plate and on the part. As you say you wear part and plate too unevenly if you use only repeated pattern. Random is king here.

I did lapped very little the better one, just to remove the burrs and it the first specimen is straight enough. measured it and left it alone for time being. I'll be watching it.

it was the second one (with marked 0,01 mm markings on it.) I was goofing around. I was trying to make top and bottom planes parallel. I know that hand lapping is not normal way of doing it. Manual lapping is generally used only to even out irregularites on one surface. And it is actually hard to keep top and bottom surface parallel if you don't randomize.

What about if you do want to use this weaknes of the method for your benefit?

You know that if you hold the part high it wears more the side on the forward stoke leading edge. I used that with the figure of eight - on forward stoke I used high grip on corner I wanted to wear down a bit more.

That heating phenomenon is a real consern. Specially when I was handling the part with bare hands (well nitrille gloves) and washed it well with soap and warm water, but I allowed some time to settle.

I'll repeat the measurement and see if changes today.

You are right on thet one too that all bases should err on hollw side to avoid rocking. I though of getting it firs almost straight and then just a tad more from the middle.

Pekka
« Last Edit: December 25, 2016, 10:00:27 AM by PekkaNF »

Offline Pete.

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Re: Recommend prismatic type universal indicator stand
« Reply #13 on: December 25, 2016, 06:25:48 AM »
Flat is all you need for an indicator stand. If you were going to use it as a comparator then parallel too.

Also, given the method you're using to check it, make sure that the other face has no raised edges or dings. Blue it up on your surface plate to check both sides.

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #14 on: December 25, 2016, 01:11:48 PM »
Pete, now you got me on the run....with this little accuracy I assume that lapping plate is staright and check the pattern, but this is "new" plate and now my asumptions wer shaken.

Phuh. It's all good. I checked with dykem hi spot. Anyone who has used it probably understand why I did not take any pictures middle of it :lol:

Pekka

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #15 on: December 30, 2016, 02:40:25 PM »
Other side of my new two sided looks pretty good when clocked effective surface seems to be accurate to 0,005 mm or something...


Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #16 on: January 01, 2017, 05:55:19 AM »
Houston we have a problem....I think everything is straight and parallel enough, but now it sticks to granite like there is no tomorrow. It even does not look like a mirror.

Do I need to learn flaking? How do I do this without screwing it up?

Pekka

Offline Pete.

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Re: Recommend prismatic type universal indicator stand
« Reply #17 on: January 01, 2017, 06:27:05 AM »
If it wrings to your plate then you can't hope to get it much flatter really IMO. Have you tried laying it down and giving it a push to see if it floats?

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #18 on: January 01, 2017, 07:45:34 AM »
No, it sort of "sticks" to best granite surface plate, glides and "rings" over old granite surface plate.

Now the funny part is that it behaves well the cast iron lapping plate and cheap cast iron surface plate.


Pekka

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #19 on: January 02, 2017, 10:12:39 AM »
Cleaned it up and ground a bit more, used much blue to show that bearing is not complete and not that smooth.

It is fine for most of the use, I'm just wondering the "stick". Now it glides over the granite plate if moved faster, but when left alone for a moment it "sticks" to granite.

It does not wring cast iron lap plate or surface plate, but for wringing you would a better surface than you can produce to cast iron?

I checked the foot of the height gage and it has nice bearing and feel on the surface plate.

Pekka

Offline Pete.

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Re: Recommend prismatic type universal indicator stand
« Reply #20 on: January 02, 2017, 10:44:46 AM »
That bearing looks fine to me, it's normal for the middle to be slightly hollow to prevent rocking.

Online PekkaNF

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Re: Recommend prismatic type universal indicator stand
« Reply #21 on: January 02, 2017, 02:00:28 PM »
Tht what I was aiming for...other one had all bottom coming flat at once. I held my hand on the middle for maybe 30-40 sec and had short go....you almost can see my handprint on it. :wave:

Tried to find my scraper. Where on earth I put that one?

Pekka