Mike,

If I have understood your predicament correctly, instead of "adding thickness" to the side plates, I would personally remake the mating pieces in thicker material to 20 thou thicker. They look to be the easier to construct and from less expensive stock.

Is the fact that there is extra clearance that critical? Depending on the construction, a large brass, or similar, washer might take up the "slack"?

There's more than one way to skin a cat. I have no doubt others will come along soon with more ideas.

John

I don't know the component, but wonder if you can take the same amount off of the rest of the same component? From the picture I would guess it to be at least 3/8" thick, so at most there would only be a 5% reduction in stiffness.

Brian

Mike,

Without knowing the design of the tool, I was just throwing a few ideas into the ring! Think of the washer idea as similar to using one of the Teflon-style coatings used to refurbish machine ways. Twenty thou is pretty thin – a piece of brass shim that thick secured with superglue would probably withstand what little load there is on the tool when in use.  ( Even if it meant machining a bit more off to accommodate it .)

John

Edited to add the afterthought in brackets.

Edited By John Hinkley on 22/07/2019 15:36:02

Fixing your errors in a sound and practical manner is one of the things engineering is about.

Everybody makes them, but not everybody owns up.

If the side plate step is where I think it is, some sort of shim 20 thou thick should work, but you need a way to stop it slipping out. I think I'd try drilling and tapping a couple of (say) 5 BA or M3-ish holes through both sideplate and shim and put screws or studs in to anchor it. Don't think you can have them protruding on the inside, so you'll need an exact length and Loctite 271 or suchlike would probably help. Whether you can remove invisibly or otherwise disguise the outer ends, countersink, or just leave them visible, is largely an aesthetic/social decision.

I'm sure there are other solutions: quot homines, tot sententiae.

Edited By Mick B1 on 22/07/2019 16:56:52

I would either make the ‘mistake’ as large as possible and replace the removed metal with something as thick as possible, before re-machining, or remake the easier part(s).

In this case, it might be a simple case of filling with a good bearing material, if the load is minimal and it just needs to be a sliding fit. Maybe drilling holes as a key, in some cases c an bne. Advantageous.

All mistakes can be corrected, by changing dimensions of other parts, repairing, or replacing. Sometimes one just starts again, from scratch! Every instance will have one or more options and each will need its own particular problem considering, before continuing. Some items are heavy load-bearing parts, and some are simply supportive. Consideration of any load-bearing part being altered should take into account the risk of later failure.

Even the order of making parts can help in reducing errors or making it easier to recover a mistake. Like carrying out the difficult machining operations before spending a lot of time on the item. Scrapping a complex item because of the last machining operation going wrong is the worst scenario!

It must be catching! Yesterday I returned to the mill to continue machining a 3mm thick plate on which I'm mounting a small electric motor. I'd spent quite a while getting it nice and square and drilling a number of holes correctly. ( DRO helps. ) I set it up ready to drill the hole for the motor spindle to poke through. Next day and too late, I realised that I'd mis-read the diameter dimension as a radius, and drilled the hole twice the size it should have been. Then spent over an hour trying to remedy the mistake by "bodging". Gave up in disgust with myself and now I'm off out to the workshop to remake the part from scratch – what I should have done in the first place.

Sometimes you just have to look big and "pay up".

John

You could thin the pivot end of the arms down by 10 thou a side.

I do not make "Engineering mistakes", I make Cock up*s ! Sad to say, they can seldom be "Repaired"

Anyone else like that out there? can we form a club ?