# Knurling some alloy spacers.



## blackrodd (11 Mar 2016)

Using my Unimat SL, I have made a 15mm to 16mm spacer for my saw blade, which took me ages, but was interesting and fun, after making something this small, items a bit bigger should be easier.
First problem was the 1/4" tailstock drill chuck, much too small for any drilling or milling work up to 12mm,
So long story short, I bought a 50mm 3 jaw chuck from Chronos, 12mm thread so it's now my drill etc chuck and came with a base for the milling slide, with 4 fixing bolts and tee nuts, so multi use. 
Now I would like to knurl some spacers, 12mm x 4mm thick. I can mount them on a threaded bar singly and lock nut them tight each side, mounted in the 3 jaw chuck and centred in the live centre in the tail stock for stability. 
I have a single wheel straight knurler at 1mm, As I have nothing to practice on, Is there an art to this knurling anything to watch out for? Or should I make some spacers and have a test run?
Then I'm on to some top hats for my kity cutter block, 15mm inside, 20mm outside and 40mm long after the "Hat"
Many thanks, Rodders


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## CHJ (11 Mar 2016)

For best knurling profile choose a knurl pattern/knurl wheel size that matches/divides into as near as possible the circumference of the part.

Knurl a length of the stock bar first and then drill/bore followed by parting off at required thickness/length with revolving tailstock in hole/bore.


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## alphatec (14 Mar 2016)

+1 For above with caveat, be careful when your parting off that your parting off tool does not cut into revolving center.


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## chaoticbob (16 Mar 2016)

Did this work out? In general, single wheel knurling isn't a good idea on a small lathe because of the stress it puts on the spindle bearings and the cross slide feed, maybe OK in alloy tho. I'd be interested to know. A scissor (straddle) type tool might be a better option if you can find one that fits your machine.
While it makes life easier if the circumference of the workpiece is an integral multiple of the knurl pitch, in practice that isn't always achievable, and certainly isn't necessary. The wheel should 'self register'. To make that happen you need a heavy feed and low rpm so that the pattern is cut deep enough on the first revolution of the workpiece for the wheel to 'find' the pattern second time round. A certain amount of boldness is necessary! 
Parting off with tailstock support can cause problems. The parted-off bit can't fall free, and when it loses support from the parent stock it can tip over and cause a jam-up. That isn't just theoretical knowledge! Same with cutting wood I suppose - you've got to give the offcut a safe escape route from the cutter.
Robin.


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## woodpig (17 Mar 2016)

chaoticbob":rhf4h777 said:


> While it makes life easier if the circumference of the workpiece is an integral multiple of the knurl pitch, in practice that isn't always achievable, and certainly isn't necessary.
> Robin.



Yes that's very true. Theory and practice don't always agree. I couldn't tell you what the pitch is on my knurling wheels is but it hasn't stopped me getting decent results. Once in a while it doesn't produce a decent knurl but a quick skim and a second attempt gets the job done. I suspect this would sometimes be the case even if you did get the circumference to match the pitch.

I use a home made scissor type tool as the one I bought was quite sloppy. I'd like to try a cut knurling system but the tooling is I suspect very pricey.


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