Knurl Tool Project (clamp type)

[Ray C]

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

 

[Ray C]

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...

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.

 

[itsme_Bernie]

"Subscribed".


Bernie

 

[Ray C]

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

 

[Maxx]

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.

 

[DAN_IN_MN]

Looking good!

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

Glad to hear the stitches are out!

 

[Stonebriar]

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

Rick

 

[Ray C]

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

 

[Ray C]

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

 

[Ray C]

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