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Knurling tool operation

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Nick Clarke 322/11/2019 17:37:03
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460 forum posts
12 photos

Have just ordered a knurling tool of the clamp type - I wish to use it to finish some parts of the Hemingway/Thomas height gauge.

I have never used a knurling tool before so some suggestions for lathe speeds and whether to do it under power (at present I assume this is correct)

The parts are about 1 1/8" mild steel and 5/8" brass.

Thanks for any help.

OuBallie22/11/2019 18:32:06
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1149 forum posts
661 photos

Nick,

Experiment on a scrap piece first as you may need to adjust my method.

My technique using Hemingway kit I made is as follows, with lathe running:

1) Wind Cross-slide forward until knurls are centred over workpiece, then turn the screw until they make light contact and just start revolving,

2) Wind Cross-slide back,

3) Give the adjusting screw 1/8-1/4 turn

4) Slowly move Cross-slide forward forcing the knurls onto the work until centred, then another 1/4-1/2 turn

I find that this method ensured the knurls are in sync and produce perfect knurls as evident:

Hemingway Knurling Kit
Hemingway Knurling Kit

Geoff - Recovered from the Stent procedure, and complications, I had end July

Brian H22/11/2019 19:42:04
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1346 forum posts
100 photos

I find that you need a slow speed on the lathe such as lowest backgear and, if you can, flood with coolant to wash away any chips that would otherwise be crushed back into the knurl.

Brian

Andy Carruthers22/11/2019 20:02:40
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262 forum posts
23 photos

Top tip from Hopper - lightly dress the knurled part with a file to remove any sharp peaks

Vic22/11/2019 22:15:49
2386 forum posts
12 photos

I’m waiting for the Chinese to start making these: laugh

**LINK**

not done it yet23/11/2019 08:46:07
3796 forum posts
15 photos
Posted by Vic on 22/11/2019 22:15:49:

I’m waiting for the Chinese to start making these: laugh

**LINK**

Is there any reason to believe they are not made in China?

Martin King 223/11/2019 09:18:05
640 forum posts
240 photos

NDY

Does say "Made in Germany" on each tool?

Cheers, Martin

not done it yet23/11/2019 09:52:06
3796 forum posts
15 photos
Posted by Martin King 2 on 23/11/2019 09:18:05:

NDY

Does say "Made in Germany" on each tool?

Cheers, Martin

Thanks. I only hunted though the printed matter. Didn’t try to read the small print on the small pics!

roy entwistle23/11/2019 10:09:27
1092 forum posts

Have a look at the price

Roy dont know

JasonB23/11/2019 10:20:37
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Moderator
16917 forum posts
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Posted by Vic on 22/11/2019 22:15:49:

I’m waiting for the Chinese to start making these: laugh

**LINK**

You can get yours on order Vic, plenty about from not only China but Taiwan and India toosmiley

peak423/11/2019 10:27:41
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958 forum posts
89 photos

I'd pondered on making one of these , to Gadgetbuilder's design some time ago, but never got round to it, and then a house move got in the way.

Bill

Clive Foster23/11/2019 11:06:40
1950 forum posts
70 photos

I have ordinary bump knurls, a Brauer hand squeezed 3 wheel "nutcracker", and a Marclo professional clamp type knurling tools. Sometimes tempted to make a DIY cut knurl tool too just to see how well they work.

Rule 1 seems too be use good quality sharp knurls. The knurls do wear, especially if you show them obdurate material. Best to assume the ones on a used "bargain" are shot and that the ones included with an economy device aren't up to scratch. Dunno what were in the Marclo when I got it but a bit of stainless steel put a nice flat on one. Knurling stainless can be iffy due to work hardening but I'm pretty sure the wheels weren't OEM quality. Got replacements from Zoro which seem good, acceptable price and quick delivery.

The Marlco has a hand lever to apply knurling pressure after the basic knurls just kissing the work setting has been made using the screw. Makes the whole process much more controllable as compared to relying on screw feed. Whether via cross slide for bump tool or via the adjuster of the basic clamp type. The nutcracker looks rather lightly built and a bit cheap but works unreasonably well on the more ordinary range of materials. It will do silver steel if you insist but thats being unkind. I'm convinced that the control and feel from hand squeezing or a hand lever makes the difference.

Much internet talk about getting the work size right so the knurls fit round equispaced, gear tooth style. Waste of effort in my view. Unless the job is small and the knurls coarse the difference between dead right diameter and worst possible case is small, a few thou usually. In practice knurling is a combination of cutting and displacement so things soon shave to fit if displacement alone isn't enough. Hence the desirability of coolant to wash away the thin shavings.

If you need the OD dead to size perhaps calculating the start diameter is desirable but I just have at it. Even coarse knurls on a nominal 3/8" diameter shaft went just fine with the nutcracker.

The Marclo is very heftily built. Much stouter than the common DIY clamp designs but can still deflect a little if you get careless. I'm inclined to believe that stoutness is important for easy, reliable results and that the usual DIY proportions are inadequate for anything much over an inch diameter. Being a bit on the light side doesn't stop the DIY breed from working but it just makes it harder as more care its needed.

Clive

Nick Clarke 323/11/2019 13:37:18
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460 forum posts
12 photos

Thanks guys

Nick

peak423/11/2019 14:43:13
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958 forum posts
89 photos

Posted by Clive Foster on 23/11/2019 11:06:40:

...............

Much internet talk about getting the work size right so the knurls fit round equispaced, gear tooth style. Waste of effort in my view. Unless the job is small and the knurls coarse the difference between dead right diameter and worst possible case is small, a few thou usually. In practice knurling is a combination of cutting and displacement so things soon shave to fit if displacement alone isn't enough. Hence the desirability of coolant to wash away the thin shavings.

.....................

Clive

 

I watched this video last night before you posted your reply.

The presenter makes the same point very well, if in a rather long winded fashion. Fast Forward might be of use to the viewers

Bill

Edited By peak4 on 23/11/2019 14:43:47

robjon4424/11/2019 14:44:26
112 forum posts

Hi all, indeed the cut knurling tools on Mr Cutwells site are indeed works of art ( or tool pornography ), the secret being that the shafts that the knurls attached to are geared together at the other end inside the head of the unit to prevent mismatches of the pattern. Used them a lot on CNC lathes, to make them cut of course the wheels have a substantial angle into the front face, probably 10 degrees or more which produces a stream of fine chippings & gives an excellent form & finish on the product meant to be seen, clutch alignment tools for BMW motorcycles as an example, in shedloads. The single wheel ones are for straight knurling & work in exactly the same way, I have an example in front of me, a wheelstud & the knurl on it to be pressed into a wheelhub has a mirror finish, again made in thousands. However I did test that one out on a manual lathe out of curiosity & it performed flawlessly, therefore if you could acquire such a wheel or modify an ordinary hardened steel one on a T&C grinder? Finally I have in my Private Collection a 3 wheel version of this type of cut knurler that can definitely be used on a manual machine, it features 3 longitudinal arms with knurls on the ends & knurled ring on the body to wind in or out to the required size, so skim a bar end to size, establish knurl size then let it rip on the job in hand, I've been castigated many times on here for using industrial sized tooling, however in my working lifetime there have been many opportunities to acquire such items at little or no cost which in a home workshop environment would likely last forever

BobH

Howard Lewis24/11/2019 15:31:45
2607 forum posts
2 photos

For a long time, I agonised over the n"gear ratio" between the knurl wheel and the workpiece. Should ,it be an exact integer? In the end gave up, and seem to produce the desired result.

As an Apprentice was told to apply a 0.010" D O C, but do it by "guess and by God".

I know when I have overdone when the knurls shear off from the workpiece, and i have to start again.

As usual, almost the last operation!

I often knurl under power feed. If the first pass does not produce a deep enough knurl a second pass with a deeper setting engages the knurling wheels with e first cut, like meshing two gears.

Clamp type tools impose far less strain on the bearings of the lathe than a tool being forced into one side of the work.

There are tools available which truly cut a knurl, whereas the ones that we use mix forming and cutting the metal.

Applying coolant is a definite benefit, but not with a brush! The bristles get caught and that can spoil the work! DON'T ask.

Howard

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