slitting saw speed

I bought an arbour at the Midlands exhibition & have been given a handful of 3mm saws. I went to use one today & was surprised that it would cut nothing.

The blade is 80mm diameter, 3mm th, & tooth pitch is 8.5mm point to point.

I wanted to form a tongue in the end of a piece of 9.5mm diam chromed steel shaft taken from a photo copier that I am using for the piston in a hand feed water pump for my traction engine. (where it joins a slot in the handle)

If I ran the cutter slow ie 100RPM it just bounced off the steel & as I increased speed to 650 RPM it just created sparks

Can someone advise me on the correct RPM for a saw of this diameter & tooth pitch please. I have several so will try others although this one seemed really sharp at first- It is HSS.

I have not tried a milling cutter yet but it may be that the steel is very hard but i think not as it seemed soft in the middle when I cut it to length.    It is just that I thought that i would try it out the saw as i could clamp the rod horizontally, take a slice of the top, drop the cutter down & take a slice of the bottom & leave the tongue in the middle nice & parallel

Edited By Sam Longley 1 on 24/10/2017 21:19:57

Is the blade rotating in the correct direction? Surprising how easy to make that mistake, don't ask how I know.

Dave

That would be an "egg on face moment "

I will check in the morning. I did that once with a spindle moulder. Bits of cutter flew all round the workshop !!!!

Surface speed in mild steel would be around 100 ft/min or 30 m/min. The 100 rpm should have been fine. It is possible the shaft is surface hardened.

Look at the teeth of the cutters under 10X magnification. The fact they were given to you means they could have been used and need resharpening.

You do sometimes get steel shafts with intensely case hardened skins, but soft inside. I can remember trying to machine some knitting machine pushrods that I'd been able to cut with a hacksaw, but couldn't turn with HSS.

If by chromed steel you mean chrome plated, that could be the problem. Chrome plating can leave a very hard coating which may need to be ground off before attempting any other machining. I tried drilling a chromed bar and the drill glowed red as its tip deformed.

Roy

That may be the problem as the centre looks like honeycomb in comparison to the surface. Perhaps I should try some other steel as a test

Use the same rpm as you would use if turning a bar of the same diameter as the slitting saw in a lathe.

They don't work like abrasive cut off saws at thousands of rpm.

Sam

If the shaft is one of those that the print head traverses on, it will be as hard as hell on the surface.

Very interesting observation, that. I've always thought that they were Stainless of some grade. I've got quite a stock of printer rods in various diameters and from different makes and have never had any problem machining them and getting a very good finish using HSS tools. Guess I'm just lucky.

Dave
The Emerald Isle

from bitter experience - run it slow...real slow and all will be good

Sam - I have a draw full of printer cartridge guide rods, scanner guide rods and guide rods from photocopiers. Maybe some machines use hardened rods but I have yet to come across any. It all machines like a dream and leaves a lovely finish.

My guess is that the cutter you used is either very blunt or you are running in reverse or both.

Try turning a bit in the lathe to prove or disprove.

Rik

PS How do you know it's chromed?

If my experience is anything to go by, it's the people who get a hard one who are unlucky. The very first rod I tried to turn was hard enough to defeat carbide. Very discouraging! Since then all my other ex-printer rods (10+) have machined without problems. It may be to do with the printer type. The very hard rod came out of a hefty HP Office Printer that worked hard for a living; all the others from lightweight domestic types.

Dave

Solved it with a 70mm diam carbide tipped blade 2mm th running a 200 RPM

Thanks for comments

I've come across both, really nice ones and ones that turn like a ploughed field.

Neil