Holesawing Steel Plate

[Citroënbender]

I’ve got to organise a custom tool, to counterhold a crankshaft.

It’s basically a ring of steel 8-10mm thick welded to a handle around 25mm wide by the same thickness by 400mm long.

The ring part will have multiple 8mm fixing holes drilled on a 49mm PCD. It will be about 70mm OD and needs a centering bore of 35mm.

Cutting the handle, ring OD and drilling the 8mm holes present no issues. I’m just wondering about real world approaches to drilling the centre hole, Google is one thing but I’m interested to hear from people who’ve sawn holes like that in basic garage workshop situations, with commonplace tooling. As in, will a bimetal holesaw do the job if used slowly and gently?

[.:4:.]

So material depth and hole size and amount of holes?
Either way trefolex will be your friend

[simon varley]

have you considered laser cutting the whole thing?

[hawke]

I have a basic garage workshop, so would cut such a hole with lathe or mill. Mill will easily do holes on that PCD.

[Citroënbender]

We have just a drill press, welders, bench grinders, small linisher. Milling and turning are farmed out to a semi-retired fellow in the area.

Simon - I can’t see myself finding it laser cut by 4PM tomorrow, off a paper sketch, for $120 or so outlaid. Would be great if I could!

[Interceptor]

Wouldnt be the first time i've used a hole saw, plenty of lume and even more patience with a holesaw, just go slower than the federal government

[whynot]

It is possible to do a test hole on a scrap bit of identical metal first? Hole saws are great on the softer metals, but struggle on the harder grades. Biggest problem might be the hole saw wandering around a little with hand tool application, even with a pilot hole. If it is slow going the pilot drill starts digs into the sides of its pilot hole, expanding it, resulting in drill wobble. What type of accuracy do you need, both for hole location and hole size?

[Citroënbender]

I’m essentially knocking off this: https://www.ozwidetools.com.au/bmw-n...t-holding-tool

Centre bore accuracy required is “tidy” as opposed to “sloppy”. Highly scientific terms.

Counterhold torque loading is 300Nm, hence the use of thicker steel plate.

[Charliewool]

Do you have oxy?
Make up a gadget similar to this..


(Doesn’t need to be as fancy!)

Centre punch in centre of circle to be cut, drill a small pilot hole on perimeter of diameter to start the cut, and cut your circle!

[Citroënbender]

That’s a nifty gadget! I haven’t seen an oxy cutter head around though, and don’t have one at home.

[Charliewool]

Originally Posted by Citroënbender

That’s a nifty gadget! I haven’t seen an oxy cutter head around though, and don’t have one at home.

You get what I mean though?… You set the pointed tip distance to centre of oxy cutting tip to 1/2 the diameter of the required hole size and rotate the torch with the pointer tip in centre-punch.
Pilot hole on the circumference is to start your cut and avoid blow back.

[Citroënbender]

Yes, totally understand the idea and have new tool envy.

[Interceptor]

Originally Posted by Citroënbender

That’s a nifty gadget! I haven’t seen an oxy cutter head around though, and don’t have one at home.

Geez.... the one I made in high school is still somewhere in my toolbox!

[AMB]

Originally Posted by Citroënbender

....needs a centering bore of 35mm. ....will a bimetal holesaw do the job if used slowly and gently?

Yeah, should do, buy a good quality one to make it easier. I've done similar, even stainless. I would stop half way through, flip it over and finish from the other side. Just dont overheat the blade. Sometimes I air cool with compressor air while cutting, it helps a lot and sometimes easier and less messy than trying to keep cutting oil up to it, depends on the circumstances.

[Charliewool]

Originally Posted by Interceptor

Geez.... the one I made in high school is still somewhere in my toolbox!

Ditto… left mine at work when I retired

[ozrunner]

Go for it it's a piece of cake. Done this many times in 10mm plate.

But you must use a quality hole saw and a proper drill press for accuracy etc and at a medium speed and use plenty of lube as it will get hot. I usually use WD40. Used trefolex as well but its messy compared to WD40 and stinks

[cs123]

35mm annular cutter in the drill press?

[Jack91]

I've gone through 16mm s/s plenty of times with a holesaw in a geared head press.
Just clamp it straight to the deck with blocks and lock everything up, finished size will end up a mill or so bigger.
I exclusively work with stainless and I find cutting oil better than trefolex (has a better cooling effect being able to submerge the cut), but whatever you use just use a lot of it. You'll be surprised what even the cheap Sutton holesaws can do if you keep them relatively cool and clamped up tight.

[Citroënbender]

I’ve only got partway through the job today - everything else possible, jumped in front of it.

I bought 8mm ground finish plate, have done the internal setout but not marked the periphery for cutting to shape. My own drill press and the workshop one are both older Asian made belt drive units - all pilot holes went fine, so I’m confident. Filing corners of the 1/2” square recess for the breaker bar end, will be a small challenge for the ego to make neat.

This is the thickest I’ve played with in steel, previously only got up to 4mm black plate to make a customised exhaust bracket. I appreciate the seasoned advice/encouragement from all.