A fun project
Posted: Fri Jan 25, 2013 8:55 pm
This is a fun project if you have some time to kill and want to be productive.....a hand knurling tool. i got the plans from a machinists magazine and if anyone wants a copy of them , I'll be glad to send them along. It's made out of a piece of 3" x 4" x 3/4" piece of mild steel, some drill rod and some threaded rod. You'll need a mill, or access to one, to do the slotting and some of the other cuts. There wasn't any welding involved in the original plans, but i changed some of the features from the original, so there is some welding if you follow what i did. I included an isometric of the original plans above what i did to show the differences. Hopefully I made it better?!
The 1st picture is the isometric, under that is what i did. The first change was the dowel pins that held it all together. Dowel pins were also used to lock in the knurl wheels, but i wanted to be able to change out the wheels for a different diamond or straight line pattern, so I bolted everything together using 1/4-20 button head cap screws. The caps screws also work as axles for the knurl wheels.
The second change was purely cosmetic, i moved the guide rods in an 1/8th on center toward center. It doesn't affect anything , I just wanted to see a little more "beef" outside of the guide rods.
The third change is on the drive screw . The original plans call for just a piece of drill rod through the drive screw to help turn it but I prettied mine up with a knurled knob that is drilled through and welded to the allthread. It still needs a drill rod through it for torque, though.
The fourth change also involved the drive screw. The original plans only called for the drive screw to push the middle piece down into whatever was being knurled but I wanted the drive screw to not only push down but also to pull up the middle piece. To do this I drilled and tapped the top piece for a 3/8-16 right hand thread and the middle piece is drilled and tapped for a 1/4-20 left hand thread. I turned down 1 inch of the length of the allthread down to .243 and gave this a left hand thread on the lathe. The reason I went less than a 1/4 inch (.250) on the guide screw was to get a loose but workable fit on the thread. Too tight and it would most likely bind up, too loose and it would fall out. The last picture shows the allthread, one piece with nothing done to it , one turned down to .243 and one with the 1/4- 20 left hand thread. If you decide to do this change, i would advise adding an extra 1/4 inch in length to the turned down part if you want the middle piece to go all the way up to the top piece, but it isn't neccessary.
The middle piece needs to slide freely on the guide rods, so the author suggests reaming the holes to .376 , but if you don't have that exact size reamer, a size 'V" drill bit will also work fine at .377
Other Steve
The 1st picture is the isometric, under that is what i did. The first change was the dowel pins that held it all together. Dowel pins were also used to lock in the knurl wheels, but i wanted to be able to change out the wheels for a different diamond or straight line pattern, so I bolted everything together using 1/4-20 button head cap screws. The caps screws also work as axles for the knurl wheels.
The second change was purely cosmetic, i moved the guide rods in an 1/8th on center toward center. It doesn't affect anything , I just wanted to see a little more "beef" outside of the guide rods.
The third change is on the drive screw . The original plans call for just a piece of drill rod through the drive screw to help turn it but I prettied mine up with a knurled knob that is drilled through and welded to the allthread. It still needs a drill rod through it for torque, though.
The fourth change also involved the drive screw. The original plans only called for the drive screw to push the middle piece down into whatever was being knurled but I wanted the drive screw to not only push down but also to pull up the middle piece. To do this I drilled and tapped the top piece for a 3/8-16 right hand thread and the middle piece is drilled and tapped for a 1/4-20 left hand thread. I turned down 1 inch of the length of the allthread down to .243 and gave this a left hand thread on the lathe. The reason I went less than a 1/4 inch (.250) on the guide screw was to get a loose but workable fit on the thread. Too tight and it would most likely bind up, too loose and it would fall out. The last picture shows the allthread, one piece with nothing done to it , one turned down to .243 and one with the 1/4- 20 left hand thread. If you decide to do this change, i would advise adding an extra 1/4 inch in length to the turned down part if you want the middle piece to go all the way up to the top piece, but it isn't neccessary.
The middle piece needs to slide freely on the guide rods, so the author suggests reaming the holes to .376 , but if you don't have that exact size reamer, a size 'V" drill bit will also work fine at .377
Other Steve