MetalworkingFun Forum

thinking caps on please ....ive been trying to work out the easiest way to cut the slot in some tube in the pict below .im making a internal throttle an clutch for a mates 120r triumph so far I have made all the bits I need but this slot has me stumped my opinion is cut it with a hacksaw but maybe one in here might have a better easier an faster way ..

4th axis on my CNC mill would do that easily with a slot mill and about 5 lines of G code

(08-17-2016, 09:09 AM)awemawson Wrote: [ -> ]4th axis on my CNC mill would do that easily with a slot mill and about 5 lines of G code

Exactly what I was going to suggest.

that's great if I had a cnc setup on the mill

OK then.  How 'bout a horizontal with a universal table and dividing head including the gear train and a vertical head?

A tracer attachment on the mill also tied to the table travel should also work.

I think he only has a mini mill and lathe at his disposal.

You could do it by holding the piece in the lathe chuck and then drill a series of holes using a hand-held drill. Then clean up with a file. You may be able to make an attachment that bolts to your cross slide and holds the drill firmly in place.

Other option is to drill the start and end holes and then join them up using a rotary tool (e.g. Dremel), using the metal cutting disc and then finish with the sanding drum.

Personally, I'd go for the second option.

Wish I had even the third axis (under CNC control) on my mill. 2 axis with manual Z is what they call it. :(

Another option might be a ball mill, hold it in the vise, swivel vise to 45º and cut. Rotate part a little, cut again.

If you have an indexing head, you could calculate the table travel necessary for each index and drill a hole. Then file the left overs.
Isn't an easy piece to make.

It seems to me that if you can figure out a thread pitch for it and have the gears to make it happen, it'd be trivial on a lathe. Or if you have ELS installed on your lathe you don't need to worry about the gears.

ELS = Electronic Lead Screw - https://groups.yahoo.com/neo/groups/E-LeadScrew/info

On the lathe: rig a tool post mounted milling spindle holding an end mill. set gear train for your coarse thread and cut the thread. Probably best hand turning the main spindle rather than using power. A simple milling spindle belt driven from above was very common to see in home work shops before cheap import mills arrived on the scene.