Slot Drill problems

Whenever I use a slot drill to machine a fork end or slot I usually end up with an oversize irregular shaped slot.

You have slop somewhere and the wonky slot proves it. Stiffness is everything when you mill in a lathe.

If you are making a fork you can use the side of the cutter instead of the tip btw, don't use too high a speed, a nice whirring speed(300-500) that munches the metal away quietly works best for me

Usually the milling slide is the weakest point, I had to beef up my ML7 one on my M series Drummond with a better chunkier cross slide t-bolt and I also use stops to prevent it from twisting under load

Then there's the other slides, they all need nipped up

If you get any noise instead of a nice quiet whirring munching sound then something ain't right

I nearly forgot

Use a cutter of about 6mm to 8mm max, preferably a 2 flute cutter, (I find 6mm best)

A 6mm cutter will make a 12mm slot two to ten times faster than a 12mm cutter can achieve on a hobby lathe

I must get around to doing this on my Myfraud vertical slide. That and a support under the dovetail area to sit on the table and hold the working bits in place. What sort of stops did you fit to stop it twisting under load? It definitely is the weak link in the set up when milling.

I just t-bolt in anything I can find from the milling clamp set, those slotted finger clamps work fine

The original weedy (and failed) ML7 t-nut is on the left, my replacement t-nut is in the middle and a small clamping set finger on the right

The extra support from the clamping set seems to be just enough to allow a decent milling job to be done without it twisting. (I couldn't believe it when I first saw my slide twist under load, grrr)

Edited By Ady1 on 17/09/2016 10:12:36