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Victoria - hoping to get a hole bored


New Member
I'm hoping someone on the island might be able to help getting a hole bored in my headstock .

I've got the 2 slabs ganged with bolts and the position marked. The size is 8" x 12" with the hole center to be 9" from one end. It is in mild/A36 steel, each piece 5/8" thick.

I'll need it bored to 1.98" for my bearing cups, then I'll build up the rest of the headstock.

I can do any prep work or change as requested before getting it done.

I did talk to one person who could do it towards the end of Sept, but maybe someone could give me an assist before then. I'm open to compensation if desired.

Muchas gracias.



Premium Member
Hate to say it but that didn't go as planned. :mad:.
Sean came over on Friday with the plates bolted together and the first thing we did was clean up the bottom edge for a reference. Next we used the 1.750 hole saw to rough cut a hole, that worked okay. Then I set up the boring head, did a cleanup pass, measured the hole and carried on boring checking it every .030 until it was close. That's when things went sideways. I needed a press fit for the bearing race to be 1.978 and somewhere along the way the numbers in my head got transposed from 1.978 to 1.987,,,,,,,,,,, crap. Sean seemed happy just to get the holes done and said for what he was doing it would be fine but I'm p_ssed at myself for mucking it up.
To me the solution is to weld the plugs from the holesaw cutting back into the holes, cleanup the the other three edges and rebore the holes on the other end of the plate but this time do it right.
I gave Sean some .001 shim stock to make.250 wide, .004 or .005 thick spacers to put six or eight vertically around the bore and then Loctite them in when pressing in the races. That should get him to the point of trialing the spindle but after that (if not before) I'm hoping he gives me the chance to redeem myself and redo holes that will actually fit the races.
I made a holder for a pad and paper attached to the mill, why I didn't write down the target number on the pad that is right in front of my face????
Lesson learned - WDTFN - Write Down The Fricken Number.
I haven't heard from Sean since, can't say as I blame him.
Now I'll go back to my self whippings and beating my head on the wall (at the stud of course).


ersatz engineer
We've all crept up to the mark and then gone over. It is part of the ongoing perfection process - failure ot meet a goal = opportunity to learn/refine...


Ultra Member
Premium Member
I've made some errors like that. There's probably 101 ways too accomplish boo-boos, but my own are usually distraction, trying to get the job 'finished', fatigue, mental math vs calculator, or just plain human error. I've even had a CAD diagram with the dimension staring at me & transcribed the wrong number down on my notepad. My ever-evolving ritual is to somehow bold the final value (highlighter, box around, underline) vs a different symbol for intermediary values like measurements or check/target value with Example final = 1.250 vs ~1.240

Better yet, jot down a little note so you can see everything on one line. This forces you to think through it & provides something to quickly validate with a calculator. Some examples
1.250 - 0.010 = ~1.240 (Final - allowance = intermediate dimension)
1.250 - 1.234 = 0.016 (Final - measured = remaining)
1.250 - 1.234 = 0.016/2 = 0.008 (Final - measured/2 = remaining radius increment like boring head or lathe dial)
DRO reset minimizes some of this stuff but I find writing it down makes good thinking habits, kind of slows you down until the X,Y,Z positions are clear in your brain. As long as you remember to reset... click enter... don't move the setting etc. LOL

Back to your project, without seeing the purpose or loads, could you machine an oversize ring/flange turned on a lathe & press/glue/weld that into frame? Where ID = bearing OD to whatever fit, OD is whatever you can accommodate to give it sufficient meat (ie. make the holes bigger). I'd have to hunt for link when I was doing that drill press bearing/spindle repair, I recall a suggestion about bearing annular gap 'devices' for exactly this kind of issue. It wouldn't work in my application but kind of the same idea, some kind of expandable or conformable piece of hardware that marries the stock ID to bearing OD.
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Tom O

Ultra Member
I’m just releasing a brain fart here but is it possible to knurl the inside diameter to bring it back to size? I seem to remember knurling the valve guides in automotive class back in school.


Super User
I've made tons of mistakes like that, and I wish it were as simple as 'lesson learned' but I don't know that it is. I think we have a tendency to think we're a little better that we are when really we should be paying as much deliberate attention to things as we did when we were just learning. Now wait a minute, aren't we supposed to get better at things as we get older? Yes, of course we do, but we also have more to remember, more pieces to keep arranged, more ducks to keep lined up, and often less time to do it in.

I remember at a staff assembly shortly before we went into a COVID lockdown, I warned the staff not rely on their reflexes anymore and to pay attention to even the simple things that they've been doing for years because their world was about to get very different. And, sure enough, in the following months the effects were palpable with mistake after mistake. Why? Because there is only so much information we can handle at once and with the news warning us of death and destruction every ten minutes something has to give, and we let go of what we figure we already know.

I'm not suggesting the entire mistake can be blamed on COVID, but I think there is a lot more drain on our minds because of the changes to our world due to COVID than we really realize. It seems to be always running in the background, some new thing to adjust to, some new process to learn, some new PIN to memorize. So we put aside and take for granted what we know (or think we know) how to do in favour of the new things we are forced to learn. Too much on our brain, we make mistakes, and I find I'm making more and not less than I did before.



Premium Member
I’m just releasing a brain fart here but is it possible to knurl the inside diameter to bring it back to size? I seem to remember knurling the valve guides in automotive class back in school.

Ha, I had to look that up..... Internal Knurling Tools do exist. Hand Knurlers as well.


Premium Member
If it had been one of my projects I'd chuckle, call myself a dumb sh-t and do it over. It's just a bit upsetting to have someone drive for an hour each way and not go away with the expected results.
I screwed it up plain and simple, hopefully lesson learned and we move on.
As for repairs, a sleeve is an option but for the amount of work to make a sleeve I think I can rebore the holes on the other end of the plates.
Knurling - there was a big discussion here a while back and the knurling is only good for a couple of thou. I had to look up inside knurling as well, hadn't heard of it and I'm not sure where it's used.
Thanks for the words all.