LMS knurling tool help

[Pat of TN]

Hey guys. This time I have a question about using the scissor/clamp knurling tool from Little Machine Shop... http://littlemachineshop.com/products/product_view.php?ProductID=3770&category=

I have purchased this tool already, but I'm curious as to the right way to use it on my little Atlas 618. I have tried pushing the knurls into the work, and also directly tightening them down on the workpiece. I've used plenty of WD40 on aluminum. Slow speed, somewhere around 70.

Three problems. One, the arms are sloppy enough that they drift to the right when feeding. I've already replaced the crummy spring clips with bolts and nuts which removes a little slop, but not all.

Two, even when directly centered on the part, it makes everything wobble - the part, the tool, and the live center.

And third, perhaps as a combination of the above two, the knurl comes out very poorly. Regardless of stock size, even on aluminum, with coarse or medium diamond wheels, the knurl comes out very fuzzy.

It's awfully disappointing to have bought a tool like this for 50 dollars and for it to not work well. Any suggestions?

 

[Hawkeye]

Have you mapped the pitch of the wheels yet? Roll the wheel in a straight line along a piece of paper. Then mark off 20 or 30 lines with a pencil and also draw a line down the middle of your wheel track. Measure the exact distance along that line from your zero point (start) to your #20 (or 30) point. Divide this distance by 20 (or 30). This will give you the pitch. Mine, for example, worked out to 0.053".

You will have to repeat the process for fine, medium and course wheels.

I made up a table of 'best diameters' for up to 2" diameter stock. Your best diameter will have a circumference that is a multiple of the pitch. Example: (0.053 x 44) / 3.14159 = 7.42 If I wanted to knurl a shaft around 3/4" diameter, I would get better results by turning the shaft down to 7.42" diameter.

 

[David Kirtley]

Well, not an expert but for me, it has been best to do the following:

I use it in a dedicated QCTP holder set to center height.

I set my feed towards the tailstock.

I bring it into the work where the wheels are centered top and bottom on the piece.

I tighten it down to touching.

With the piece turning slowly, I tighten the wheel to get a complete knurl from both wheels.

I engage the feed and let it knurl the length and then retract the knurl with it still running.

Any more knurls on the same diameter, I leave it at that setting and feed into the work until the wheel is at the top and bottom of the piece with it rotating and let it turn a bit and then engage the feed.

To be honest, maybe I am just lucky but I don't even mess with measuring and turning to a diameter first. On the first test, I just increase the pressure until the knurl gets to a depth that comes out even. The fine knurl on mine only takes a few thousandths difference for the pattern to match up since the pitch is so fine. I probably couldn't get away with it for a coarse knurl.

 

[DennisK]

Would this be of any help?
http://littlemachineshop.com/Reference/Knurler.php

 

[DMS]

I had the same knurler when I had my 7x14 lathe (it went to the buyer of that lathe, so I no longer have it). I was able to get very nice results from it, though it is a little "loose". Getting the right diameter does help a lot. The correct method is to center the rolls on the work, one above, and one below, and then tighten the knob down. Should be fairly low speed. Lots of lube. I would recommend something heavier than WD40, like cutting oil. Knurling (except for cut knurling, which is a totally different thing) is not a cutting operation, it is a forming operation. You are basically smashing the material into a different form. This generates lots of friction, and lots of heat, hence the need for a heavier lubricant.