# Knurl Tool Project (clamp type)



## Ray C (Oct 11, 2013)

Finally getting around to making a decent knurling tool; precipitated by the fact that next week I've got a job that needs knurling.  All the knurl tools I have are somewhat sloppy and loose fitting -and that makes knurls look terrible because the rollers need to travel in a perfect axial line with the stock.  When there's slack in the arms or rollers, they go off line.   I'll be on my best behavior and make this thing very close fitting, hopefully with no noticeable slop.

So, in a fit of boredom, I drew up these plans.  -Nothing special and it's an old design.  Once I make this thing and if the design works well, I'll publish the dimensions.  It has two ranges from very small up to 1.125" and a second range up to 2.25".  Honestly, I've never knurled anything much over an inch if memory serves...

The large pieces will be made of 4150 (drops laying around) and heat treated to RC 45 or so.  All the pivot pins are going to be made of 4340 -which is considered a "super alloy" that's both hard and tough.  I had to order that material and it hasn't arrived yet.  Knurl pins need to be very hard and a super close fit.  There's a lot of pressure on them and if any swarf gets in there, it will grind soft metal to a pulp.  Also, precision fit is needed to keep the wheels from wiggling.  A grade 8 bolt stuffed in there wouldn't stand a candle's chance in a windstorm..

So far, I've carved down all the big pieces to final size and soon we'll drill the holes and do more milling.  I've been using carbide roughing endmills lately and on the pieces shown, I shaved of 0.25" with fingertip pressure on the table cranks in just a few moments...  (hint hint, consider saving your pennies and trying them out).

Here's a PDF of the tool.  Once you download it, you can click the image and Adobe Reader will allow you to use the mouse buttons to rotate and see different angles.  Also, here's an obligatory eye-candy picture of some metal fresh out of the mill.





Knurl Tool PDF:  
	

		
			
		

		
	

View attachment KnurlTool.pdf


Ray


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## Ray C (Oct 12, 2013)

HSS endmills should show a nice improvement.  Watch for temperature on those as there's a lot of friction and HSS does not hold-up as well to heat as carbide does.  I know they're a bit more expensive but used properly, carbide endmills outlast HSS by a wide margin and are cheaper in the long run.

Ray

PS:  The 1st cup of coffee it taking effect and I'll off to the shop momentarily...





shawn said:


> I'll be watching closely Ray, its posts like these that really helps out new guys like me. I did just get 4 HSS roughing end mills in the mail tonight, I'm keen to see how they do against my regular 4 flute end mills.


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## itsme_Bernie (Oct 12, 2013)

"Subscribed". 


Bernie


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## Ray C (Oct 12, 2013)

Here's a few more photos...  Moving along but -but slowly.  I had the stitches taken out of the finger and it's fragile (and a little sore still).

Anyhow, this was mainly done with roughing endmills.  First just drop a hole with a drill bit then, plunge the endmill down and use the DRO to carve out the slots.  It was all pretty-much done with one or two passes.  The corners were squared-out with a hand operated reciprocating shaper (aka:  hand filed).  Those corners need to be cleaned-up a little.  The flat sides of the inside of the passageways are nice and square.

Finally, the slot for holding the wheel was cut very carefully and as close as possible.  The wheel fits and stays in the slot even without a pin holding it.

Anyhow, the top and bottom parts are all done -just need to go over it with a hand file and get the machining burrs off.








Ray


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## Maxx (Oct 12, 2013)

Looking good!
I need to make one but my need to do list is long and that project is not near the top of the list.


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## DAN_IN_MN (Oct 12, 2013)

Looking good!

What CAD allowed you to create the interactive PDF? :+1:

Glad to hear the stitches are out!


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## Stonebriar (Oct 12, 2013)

Nice.  So are you going to press the pins in?

Rick


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## Ray C (Oct 13, 2013)

Hi...

The pins:  Yes, I'll probably press them in.  Threads would wiggle too much.

The CAD program:  It's now called "Geomagic" Professional (dumb name if you ask me) but it used to be called Alibre.  The professional and expert versions have the ability to export to many/most popular formats including 3D PDF.  There is a fairly inexpensive "hobby" version that's about $200 but I don't know if it has the PDF capability.   Anyhow, it's a very good CAD package that does almost everything that Solidworks does and it's very similar to use.  

Later this evening, I made the vertical bar and it fits very well.  I think I'm going to tweak the spacing (and the CAD drawing) between the holes in the vertical bar just a little to accommodate the ball-nose nut that tensions the bolt in the rear.  The top and bottom bars line up perfectly and have no perceptible wiggle.  Except for the pins (the material has not yet arrived) it will be finished tomorrow.  I purposely did not show in the CAD drawing, the horizontal bar that clamps in the tool holder.  I want to hold it up next to the tool post to get some ideas and figure-out an optimal design.  I'm trying to decide if there's a good reason to make it work on both the left and right side of the tool post.

When it's all done, I'll re-post the CAD drawing and also provide 2D dimensions.

BTW:  If anyone makes one of these things and needs the parts heat treated, gimme a shout and we can work something out.

... Sorry, no pics tonight...

Ray


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## Ray C (Oct 13, 2013)

Couldn't do much on this today because other things popped-up but, I did manage to drill the vertical bar and hold it together with some bolts just to make sure it moved through the full range.  I started to make the side clamping bar but, the mill vise somehow got a piece of swarf caught in the screw -so that needed attention then, a quick job came up.  I'll post that in the "what did you do in the shop today" thread.

Anyhow, here's picture of the assembled unit and it's coming along well...

I did decide that it would be nice to have it work on both sides of the QCTP which is a no brainer because all you do is turn it upside down.  I pondered welding the side clamp to the vertical bar but decided it will be bolted instead because, the heat will warp that vertical bar.

In the picture here, I was verifying that it opened to the desired amount using the inner holes assuming the ball nose nut were in place.  The range seems right at about 1.125".




Ray


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## Ray C (Oct 15, 2013)

Well darn it, the round 4340 round stock hasn't arrived yet.  -Hope it comes soon.  In the mean time the rest of it is basically all done.  Just needs a little work to break the sharp corners.  Instead of wasting a large piece of 4140 for the side bracket, I welded a few pieces of left-overs together.  The sides of the mating pieces were beveled very deeply and the weld was sunk in with two good passes of ER80s at 110 Amps.  ER80 can be heat treated.  This will be my first time heat treating welded 4140.  I've done it many times with 1045 with very good results and no cracking...

Here's a couple views of it assembled w/o the pins...





Ray


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## Ray C (Oct 17, 2013)

Here's the latest CAD design.  It's "ambidextrous" and can be flipped over or used on either side of the tool post.

Remember:  If you download it and open it with genuine Adobe (most PDF clones won't work properly) and click the image, you can rotate in all dimensions by pressing the left click and scrolling your mouse wheel or touchpad.

I'll ZIP together a more complicated set of drawings that shows the pin diameters and lengths.  They're left out of the PDF image because it makes it easier to view.  Also, won't specify the clamp bar width or the center bolt diameter as some folks may want this for varying sizes of tool holders.  

If you're interested in dimensions, send a private message... 

3D Knurl Tool Attachment: 
	

		
			
		

		
	

View attachment KnurlTool.pdf


Ray


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## fshotf (Oct 18, 2013)

Ray C said:


> Here's the latest CAD design.  It's "ambidextrous" and can be flipped over or used on either side of the tool post.
> 
> Remember:  If you download it and open it with genuine Adobe (most PDF clones won't work properly) and click the image, you can rotate in all dimensions by pressing the left click and scrolling your mouse wheel or touchpad.
> 
> ...



Hey Ray,

What CAD program do you use?  That pdf is neat!

Duncan


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## Ray C (Oct 18, 2013)

Hi Duncan...

If you look at post #9 in this thread, the CAD program is mentioned.   It's nice and I like it.  It has an Assembly function that allows you to move all the parts as though they were real and you can measure and verify all the ranges of motion.  It would be cool if the PDF allowed that too but, it doesn't...

Ray



fshotf said:


> Hey Ray,
> 
> What CAD program do you use?  That pdf is neat!
> 
> Duncan


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## fshotf (Oct 18, 2013)

Ray C said:


> Hi Duncan...
> 
> If you look at post #9 in this thread, the CAD program is mentioned.   It's nice and I like it.  It has an Assembly function that allows you to move all the parts as though they were real and you can measure and verify all the ranges of motion.  It would be cool if the PDF allowed that too but, it doesn't...
> 
> Ray



Thanks Ray - I should have read the thread more carefully :banghead:


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## Ray C (Oct 27, 2013)

It works well...  If you get the convex knurl wheels from Accutrak, it seems the best method is to position them and swiftly apply pressure until it forms the knurl properly.  Don't be afraid to stop the machine to check for a nice diamond pattern.  Apply more pressure until the patter is correct.  Then, engage the autofeed and cut the desired length.  Just make one pass.   Keep it soaked with cutting oil. I use the slowest possible feed rate on the machine.  The leading convex edge on the wheels do a nice job of slowly forming the pattern. This piece was spun at about 60 RPM.  It's about 1" diameter -soft metal.  These were the 1st two knurls cut with the new tool.

Finally, don't put anything (like your fingers) near those rollers.  Anything and everything that gets caught in those wheels will get destroyed.






Ray


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## itsme_Bernie (Oct 28, 2013)

Wow great Ray! 
This is near the top of my project list- as I have some knurling to do.

I do have a question- if you think it is OT then I can start a new topic with it-  but I wouldn't have known that a knurling could be fed?  (I know nothing about knurling)...  I would have thought it would require cutting the knurl, and then moving down to the next open section.  Thinking more about this, I guess it would make for obvious misalignments of each knurl cut that way though. 
Is carriage feeding the knurl the normal method for this?  

Bernie


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## LEEQ (Oct 28, 2013)

Looking really nice! I would love to check out that draw it on the computer and move the pieces around like they were real. Sounds great for a guy who can't always picture 3d from a 2d drawing. By the way, how's the finger coming along?


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## itsme_Bernie (Oct 28, 2013)

shawn said:


> Great looking tool Ray, and it seems to work brilliantly. Bernie, I have stopped trying to figure this one out in my head but you can hand feed the carriage when knurling and it still comes out great?



Thanks Shawn- 

It doesn't seem like it should work, like the last row of knurls would start to be chewed up as the carriage moved along.  I am sure not arguing!  I have to make a clamp style like this.  I have tried the old-push style and it cam out like crap!  Maybe I'm not feeding hard enough.

Didn't someone post a table of the TPI for knurl-wheel/diameter of work recently?  Where did I see that? 


Bernie


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## Ray C (Oct 28, 2013)

Some replies to the last couple posts but first, I do not claim to be a knurling expert so take it all with a grain of salt...

My old knurl tools were junk.  One was the "push-in" type that are out of vogue and obsolete.  My other unit was a scissor type (like a heavy duty pair of pliers) but, it had all kinds of wiggle and slack in the mechanism -too much trouble to repair.  I think a proper set of those in good condition would work just as well as this clamp type.

The design goal was to eliminate as much slop and wiggle as possible so the arms do not change angle once the carriage is moved.  Also, I wanted really hard/tough metal so the tolerances stand a chance of longevity as the tool is used.  I was only going to make it RC 40 but while it was cooking in the oven, I decided to make it RC 50.

The wheels are convex on the edges which provides a gradual lead-in of the cut as the carriage moves.  The edge does all the hard work.  Please go to the accutrak website and look at the convex wheel so you can see what I'm talking about. 

I mentioned "swiftly establish the starting pattern" for a reason.  A knurled rod must have a diameter that falls on a proper multiple of the diameter of the wheels (which is directly related to the pitch for a given wheel).   There's a little formula to calculate this.  When you first start establishing the pattern, the teeth are not sunk-in far enough to make a full cut and during this time, the effective diameter of the wheel does not meet the needs to allow an integer multiple of tooth cuts to wrap properly around the shaft.  If you spend too much time getting the starting pattern established, all you'll do is obliterate the surface of the shaft.  I tried to get the pattern established in about 10 full turns of the shaft.  In the future, I'll see if I can do it faster than that.

I use the feedrod for consistency.  The feed is very slow.  At 60 RPM, it took several minutes (5 minutes?) to cut each of those 1.25" length segments.  As it cut, I dribbled a little dark oil on there to help flush out the crumbs.  Letting the crumbs pack-up will kill the knurl.   --- _* I can't emphasize enough, do not get your fingers caught in that pinch roller.  The top roller tries to pull you in.*_  ---

The drawings...  For some reason, the 2D drawings are coming out HUGE when converted to PDF.  That's why I didn't post them.  I'm still looking at options and settings to reduce the size.

The fingers.  They're much better; I'm back in the saddle and they don't require such care as they did before.  The wounds have all healed except on one where there's still a scab and thick patch of skin that's slowly peeling off.  They look fine and are not deformed -just an extra contour on one of them.  The tips are almost completely numb -I'd say, 60-80% depending on which finger.  The location of the scar is extremely sensitive as it seems the nerves are re-growing.  Touching certain areas feels like an electric shock.  -This is a normal and predictable side-effect.  The numbness has an advantage.  When I have to pick up something kinda hot, I use those fingers .   (For those of you who don't know, I badly lacerated 3 fingers on a heavy, sharp piece of metal. No, I didn't get them caught in a knurl tool).

Here's a copy of that spread sheet for knurl pitches...  Two formats:  One for Old Excel and one for New Excel.


Ray

View attachment KnurlPitchDiameters972003XLS.xls

View attachment KnurlPitchDiameters.xlsx


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## Ray C (Jan 19, 2014)

I guess better late than never...  I forgot to post the drawings.  Here are the main components.  I did not show the pins, the threaded rod and nut for tension or, the angle bracket to connect to your QCTP.  Those things are either obvious or, specific to the size of your QCTP.

Here you go...










Enjoy...


Ray


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## Ray C (Jan 19, 2014)

OK, here's an update so you can see the dimension on the vertical bar.  It got chopped-off the other image...


Ray


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## ksierens (Jan 20, 2014)

Great job!  I still need to make one of those too, sigh, so many projects ...


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## bfd (Jan 15, 2017)

years ago I copied the aloris type knurler made it out of just a 36 plate steel used allen head bolts for the pins it has worked well for the times I have used it. not much over the years even single pointed the 1/2-20 left handed thread in one of the jaws. now I would but a tap but then I time and liked the challenge of single pointing a 1/2 " hole fun then no patience now bill


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