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Old 03-11-2017, 11:34 AM   #11
deverett
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Quote:
Originally Posted by Herbiev View Post
Cut knurling tools are much kinder on the lathe than form knurling tools but a bit more expensive
For anyone considering a cut knurler, have a look at GadgetBuilder's version
http://www.gadgetbuilder.com/Cut_Knurler.html

Dave
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Old 04-21-2017, 07:16 AM   #12
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Default Making a cut knurling tool

I did my first knurling at school,and then some more during my apprenticeship
Never very successful,but crush knurling never is,so turned my thoughts to
cut knurling .Various homemade tools on Utube,cheap and simple and some
VERY expensive commercial units.With the little information available and a
few thoughts in my head I decided to make one.So cheap and simple I did not
think it would work,so decided to fab a cheap bodgeup to see if the basic
principles work.BOY DO THEY WORK,simple,cheap and almost professional quality at the 2nd attempt.I bought a single cheap straight knurler Ebay
simply because it also came with 3 pairs wheels and one fitted.I welded
a small piece of angle iron to a piece of flat,drilled and tapped and machined
2 no m10 cap screws to m6 shoulder bolts the packed and shimmed to centre height.Using a piece of 30mm dia steel,much tougher than mild steel I had a couple of practice runs and got a good knurl at 1 pass at 30 thou deep
Photos tell the story.Will play about a bit more before taking it to the next level
by maching a solid housing/tool to a much more acceptable standard.This is great,i have taken a video and will post when I have uploaded.WATCH THIS SPACE this has great potential.Best knurl I have ever done


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Old 04-21-2017, 08:30 AM   #13
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Default Video of first cut

https://youtu.be/TVX7lU6X_Wo
This was the first cut and was very good.Various further cuts were made
at different speed ,feeds and depths of cuts.Best knurl was obtained at
1 pass, 30 thou deep at nom 250rpm.I will try a few more with this rough and ready tool
with different materials and diameters before I make a more professional tool
Fully machined to fit directly on a QCTP or on the compound slide
Expect better things I am very pleased so far
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Old 04-21-2017, 12:45 PM   #14
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Lovely result there Baz.

I really do like posts where people are experimenting with their ideas (and other people's) in an attempt to get a finished good result.

It looks like you have really proven this simple design.

Now make one that will give you square instead of diamond pattern

John
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Old 04-21-2017, 08:40 PM   #15
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Ok that looks awesome. I think you might have just convinced me to hold off making a typical pincer style tool.

Keep going, very keen to see where you take this.
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Old 04-21-2017, 11:19 PM   #16
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Hi John,making a square pattern,was that tongue in cheek.Cant see how to make a sq patt. with horiz and vert lines.
The wheels are set at 45o each to suit the RSA which gives a sideways sq
pattern.I was intending to change the angle to 50o to elongate the pattern
slightly along the axis and give a more diamond pattern,with a few other
trial and error improvements.The ease of use and the cut pattern was of
such a good standard,it worth pursuing further improvements
Second thoughts,what would a pair of diamond knurls set at 45o produce ??
Going out to the shed now to start Mark 2
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Old 04-22-2017, 06:28 AM   #17
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Default Making mark 2 cut knurler

Started with a piece of 32mm sq x 80mm lg hot rolled mild steel
Cleaned up all around,machined to fit my std 4 way tool post
and machined the 2 knurlwheel faces at 40o rather than 45o
to try achieve more of a diamond pattern.Cant seem to notice any difference
and the orig at 45o seemed to cut better.Tested various materials from
1/2"brass,16mm dia mild steel,32 mm alum to 50mm dia tough steel shafting
with varios feeds,speeds and depth of cut.In general I would note the following-
the fine knurls 0.5p are only good for small dias.Good results on brass ,alum.
The medium knurls were best for all round use but the coarse knurls were OK forlarger diameters and aluminium.Lathe speeds were in general between
100 and 250 rpm. Fine feeds were used throughout but hand feed was ok for light cuts.
In general knurl depth was 25 to 35 thou dependant on matl,diameter and knurl pitch and took a full depth of cut on steel of 30 thou as well as up to
4 passes at 10 thou each to total depth of 40 thou.Multiple passes were easier
on the tool and lathe and each pass picked up with the previose with overriding on the cut knurl.AT THIS STAGE I AM VERY PLEASED WITH THE RESULTS and would recommend it to anybody over the scissor crush knurlers
Conclusion.The tool is easy to set up but must be on centre height,although I
machined to size and shimmed slightly just touching the workpiece until both wheels revolve confirms height.However a QCTP would be ideal for ease of setting,and if going that way then rather than make a tool to mount in the toolpost I would look at making a dedicated toolholder with the wheels mounted on to just slot into the QCTP. This is the way I will be going next
Keep this thread open
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Old 04-22-2017, 07:30 AM   #18
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It was a tongue in cheek comment Baz, but I have done it by using a straight knurl and very fine cuts around the diameter with a single point threading tool, it didn't come out looking too bad, but very labour intensive, and without my DRO's, almost impossible to achieve.

It looks like you have really got this one under your belt keep up the great work.

Also, as you may well know, there are more uses for knurling than just looking pretty and helping to hold things in your fingers.


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Old 04-22-2017, 08:10 PM   #19
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Quote:
Originally Posted by rlfervan View Post
Try watching Toms Video about knurling. It helped me understand the importance of having the correct size part to start off with.
You can do that but you don't have to, I've never measured a part for pressure knurling and I've never had a problem, you simply don't need to do it, John Stevenson once knurled a tapered bar to prove the point.
Where, according to the tool manufacturers, you really should calculate the OD is for cut knurling, the comparison to gear cutting is actually valid for cut knurling.
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Old 04-22-2017, 08:21 PM   #20
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Quote:
Originally Posted by rodw View Post
Been very interesting watching Tom's video. So what I am seeing is that the only advantage of the scissor style knurling holder over the fixed style that came with my toolpost is that the scissors allow a greater range of diameters. I knurled some 4140 the other day and while it turned out OK, it was very shallow (which I did not think was surprising for that material!)

To say the scissor style reduces the forces on a small lathe just can't be correct when its all about infeed!
A clamp type knurling tool does reduce side load on the spindle bearings and, often more usefully, bending moment on the work. With a clamp knurling tool you can knurl areas on a part, without using support, which could damage an unsupported part.
My Brown & Sharp clamp knurling tool has flats on the clamp knob so you can use a spanner on tough materials, I suspect you'd have got a good depth of knurl on your 4140 with a good clamp knurling tool.


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