Engraving on The Tormach PCNC

[phil burman]

Here is a photo of some engraving work I did recently using my Tormach PCNC. The numbers are 0.080" high. The workpiece is a low carbon steel dial (3" diameter) on a tool and cutter grinder.



Regards
Phil

[sanddrag]

OMG that looks good. Nice Work!

[LongRat]

Wow, that looks great. How did you colour the numbers and lines?

[phil burman]

Clean with a degreaser and toothbrush.
Carefully wipe on some black paint with a cloth.
Gently wipe of the excess paint with a piece of paper held flat with a finger (not a cloth).
Wipe off more vigorously when semi-dry.

I just noticed that not all the divisions look evenly spaced. This must be a camera issue as under a magnifying class all the divisions look perfectly uniform.

Regards
Phil

Originally Posted by LongRat Wow, that looks great. How did you colour the numbers and lines?

[DonRD]

Great Work Phil. How long did it take to run this part?

[JRouche]

Looks real nice. Did you have to de-burr the part? JRouche

[phil burman]

No deburring was necessary.

Phil

Originally Posted by JRouche Looks real nice. Did you have to de-burr the part? JRouche

[pstockley]

Very nice, what kind of cutting tool/speed did you use?

[phil burman]

I used a 60 degree carbide engraving cutter with a 0.2mm (.080”) tip. RPM was 4,500 (max for the machine). Feed rate was 18 mmpm (0.75”/min), real slow. Depth of cut was 0.13 mm (.050”). This cutter was probably a little to course for the divisions, which had a center line spacing of only 0.65 mm (0.025"). Possibly a 30 degree cutter would have been better, but a bit more fragile also. They are not cheap to buy and it's all to easy to break the tip, hence the slow feed rate. I use kerosene with 15% way oil as a coolant, applied with a paint brush.

I used the rotary table (A-axis) to index to the centreline of each individual number and then used the x and y axis (which have zero backlash ball-screws) to engrave the number itself. This avoided the issue of backlash in the worm gear as it was always rotating in the same direction. As the dial was of a relatively large diameter 75 mm (3”) there is no visual indication that each number was produced in the flat x/y plane on a curved surface. A scale CAD drawing of the divisions and numbers allowed me to read the necessary angular indexing for each number directly off the division scale. I had a couple of practice runs on a blank before committing to the actual work-piece. Just as well as the g code for my first attempt put the numbers all over the place.

It took something like 80 mins for the divisions and 20 mins for the numbers. That’s after about 3 days of planning, so I’m not ready to go commercial just yet.

Attached is a photo as it came off the machine.

Regards
Phil

[phil burman]

Heres the 2nd attempt at a test piece.


Phil

[BobWarfield]

Gonna be mass producing Qorn cutters?

Nice work!

BW

[phil burman]

You guessed it. The ball handles give it away. I think there are something like 18 of them. Here's a photo of it in its unfinished state from a few years back.

I tried stamping the numbers but I've never been very good at blacksmithing. So it was perfect justification, at least to me, to buy a 4-axis CNC mill. Do I here a lot of people nodding in agreement, problem is only one of them lives in this house. Don't you just love it when the only logical course of action is to buy a new machine tool? You only have to keep reminding myself, this is not a rehearsal then the decision is easy.

Regards
Phil

Originally Posted by BobWarfield Gonna be mass producing Qorn cutters? Nice work! BW