Proxxon KG 50

[Iain Allen]

Does anyone have any experience with this machine?

I'm looking at cutting brass tubing 4.5mm-6mm dia and varying lengths 22mm-32mm and quantities of 30-40, unfortunately my supplier doesn't offer a cutting service. I'd rather keep control of the cutting in case I need to change lengths.

I've been using a pipe cutter up until now but I've got to up my game a bit, also tried using an angle grinder in a jig in front of me but thats a bit OTT and terrifying. I've looked at larger saws and they also look like overkill.

The larger KG 80 is another possible option but I'm open to other ideas.

 

[Seascaper]

If you get an modern angle grinder they have a speed control which makes fine cutter if smaller items much better. I recently had to replace an old Bosch and the current new Bosch is a better machine. Use the 1.5mm cuttings discs and you should have no problem. For a straight edge use a guide, nothing too technical just g cramp something to your metal or workbench.

 

[Iain Allen]

Thanks Seascaper, I have tried the angle grinder idea 2-3 times with different discs (0.8mm) and the burr that is created on the tubing takes longer to clean up and remove than using a hand pipe cutter - I've tried and timed it. Both inside and outside edges need to be smooth and clean

A disaster ordering a Proxxon from Axminster with non delivery- another thread maybe.

I'm now converting an old drill press to accept a battery Dremel with a 90 degree cutter.

Sadly I need to do this quickly to hopefully secure a contract.

I've reverted to a hand pipe cutter and just accept its the best option available so far or until I set up the Dremel idea.

 

[Inspector]

I made what was basically a mitre saw from plywood using a slitting saw blade in an air die grinder to cut pen tubes for my wife when she was casting pen blanks.

https://www.chronos.ltd.uk/?s=slitting+saw&post_type=product&dgwt_wcas=1

When we moved from the West Coast to here I switched to the metal lathe. A 5C collet chuck with collet stops let me part them off quickly once set up.

You still have to de-burr the tubes no matter what way you cut them but with the slitting saw or parting tool in the lathe it is minimal. I suggest one of these to de-burr the inside edge. https://www.amazon.ca/Deburring-Countersink-Askwhy-Aluminum-Wood-NG1000-BC1651/dp/B09Y2N5WS8?gQT=1

Pete

 

[Iain Allen]

Thanks Pete
I'd wondered about a slitting saw set up.

The Dremel idea seems to work, I just need to make a better job of setting everything up. Its not pretty but it will work.

Yes you're right about deburring, I don't mind doing a bit by hand but the angle grinder was more than the pipe cutter and any time saved cutting was taken up with extra work deburring. There's a little bit to do with the Dremel cut but acceptable

 

[ChaiLatte]

You can minimise deburring by making a fixture for the tube.

If the tube is 6mm OD, drill a 6mm hole into a piece of metal and poke the tube into it. Put a fixed stop on the bed of the cutting machine 22mm from the left hand face of the blade, such that it is only high enough to stop the fixture moving. Add a flag stop to the fence that lines up with the bed stop.

For the first cut, cut partially through fixture and fully through tube (do not cut fully through the fixture). Lift flag, push protruding end of tube on right to eject offcut, drop flag, make second cut.

Then you only need press the tube lightly against a spinning countersink in a drillpress to deburr the inside.

With some thought, you could make one fixture to accommodate both lengths required - one slot is 22mm from the end, the other slot is 32mm from the end. To reposition, with the power disconnected, drop blade into slot and fix bed stop to touch fixture.

 

[Fergie 307]

Do you not find that a pipe cutter squashes the tube slightly?
I am with Pete a lathe would be the best bet. Depends how many you need overall as to whether the cost would be justified, although a handy tool to have.
Otherwise I would use a diamond cut off disc in your Dremel. But maybe fix the Dremel horizontally and make a simple sliding table to bring the tube to the blade. This could also incorporate a stop for repeatably cutting the same length.
I use these discs to cut copper nickel car brake pipes as you need a nice clean end for the flaring tools to fit properly, I find a manual pipe cutter crushes the tube slightly at the point of the cut, so it is then fractionally undersize which is a PITA.

 

[Iain Allen]

Do you not find that a pipe cutter squashes the tube slightly?

Yes, I do find this which is another reason for finding another method.

I have thought about using a lathe but I think the Dremel idea will be quicker. I need to cut about 50 pieces at a time and in 3 different lengths

Having tried the Dremel idea with the tube supported either side of the cut does seem to work well with minimal clean up.

I'm just waiting for a collet nut for my Dremel so I can finish off the drill press idea, hopefully this weekend.

Thanks everyone for the replies and suggestions.

 

[ChaiLatte]

Do you not find that a pipe cutter squashes the tube slightly?

When the effort is worth it, you can use a mandrel inside the tube to minimise crushing.

The crush comes about because the inside of the tube is unsupported.

The advantage of a tube cutter is zero burr either inside or out.

If you had many pieces to make, you could incorporate the mandrel into a length stop and glue it to the body of the pipe cutter.

In passing, I found this, which would allow a standard hacksaw to be used:

https://durston.com/product/tube-cutter/

In effect, what I am suggesting above would be a projecting piece of rod fixed to the black length stop, with the wheel of the pipe cutter coinciding with the slit in the vee block.

If parting off on a lathe, a stop like this is a good idea. You set it in relation to the parting tool, so the carriage position relative to the chuck is immaterial: