Knurling Problem

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jroma1

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This is a homemade knurling tool. The knurling wheels are made by Dorian,they are OD .750" x
ID .250 x .375 Wide they are coated and the TPI = 20.
My first attemot to use this tool was on a piece of 12L14 approx .700" OD result was not bad,ctr photo. A second attempt was made on a piece of 1018 .875" OD result was a multiple of lines that crisscrossed into each other resulting in one big mess.

The knurling wheels are designated Left Hand (LH) and the other Right Hand (RH) WHAT DOES THIS MEAN? Is there a special way these two wheels are to be arranged? See Photo on the top. Is there a negative significance betweeb using 12L14 as opposed to 1018.

Is the problem is in the differance in diameters. Doing the math (as described in a video) and with a TPI of 20 and using a multiplier 55 is OD = .8745. Using a multiplier of 54 I should reduce the OD to .8586. I'm going to try this in the meantime if anybody out there has suggestion,comments please respond. Thank You




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Yes, the correct diameter of the work piece makes a difference in the cleanness of the knurl. Turn off the failed knurl and try again.
 
Plug this into an excel spread sheet to find the diameter for a particular size knurl

=(1/B1/3.14159)*INT(A1/(1/B1/3.14159))

A1 = Diameter
B1 = Knurl Pitch


Example A1 = 1"
B1 = 21
= 0.985

Turn down your 1" diameter to 0.985 for an evenly spaced knurl.


Gary
 
The pitch of the knurl is the space between the teeth on the knurling wheel.

Turn the work to as close as possible to a diameter that comes out to a even number to the spacing or pitch of your knurling wheel.

Mine is .040" so any diameter divisable by .040" x 3.1416 or .1257" will work perfectly.

Do a little math and you will be suprised how much .001" difference makes!

Have fun, it's what this is all about! :D

Now go make some swarf.
 
Another suggestion is to really get a bite in there when you first start. If you get a good enough first impression the it will correct itself. If you just barely touch and you make several revolutions, you have already marked out the path the knurl is going to take, which might be the one you want, or not.
 
when I restored my 9A lathe last year, my first project involved knurling. I didn't know jack about knurling so I just knurled. It did overprint but I thought it was cool anyway.

Now that I read how to do it, my head hurts from the math, but I went and downloaded all the instructions here and photos from the link provided so next time I do it right

I got a dumb question

When you knurl do you engage the lead screw like you do when making screws so the knurl runs down the round bar or do you lock the carriage, knurl one segment, move the carriage manually and do the next?

Sorry for dumb question

daveV
 
The good thing about the formula I posted above is that it works with all knurl pitch sizes and diameters.

I have knurls that are 15, 21, 30 and 60. It does all the math for you.

The pitch is usually stamped on the side of the knurl.

Gary
 
Don't disengage unless you want a very special effect. You can use the leadscrew to feed, or just turn by hand, but once you engage, stay that way till you cut the full length. If you want to re-engage, turn the part by hand while tightening the knurls down, helping them find their place as you go. Also, make sure you use plenty of oil. This is not a cutting process, but a forming process. Lots of heat and friction.
 
Great info, never had nice knurls like I have seen, and now I know why. :)
 
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