Milling/Routing Brass Sheet

Advert

New Replies

Report Bug

Help/FAQs

Milling/Routing Brass Sheet

This topic has 9 replies, 5 voices, and was last updated 16 August 2022 at 11:33 by Steve Crow.

Viewing 10 posts - 1 through 10 (of 10 total)

Author

Posts
15 August 2022 at 18:01 #609751
Steve Crow
Participant
@stevecrow46066
I've had a go at crossing out some small clock wheels on my Sherline rotary table and mill. Here's a 48 and 73 tooth wheel. And a penny.

These are straight off the machine with a "fingernail" deburr.

I drilled out the corners first with a 0.4mm bit then milled out the rest with a 1mm 2 flute carbide end mill. The material is 1mm CZ120.

There was a lot of trig and calculations to get the indexing right but I'm quite pleased with the results. With the 0.2mm radius corners, there is a minimum of filing to do.

My question is, is there a better tool than a 2 flute end mill for this process?

I have been taking depth of cuts no more than 0.3mm so 4 passes to get through. Does any one know of a bit that could do this in 1 or 2 passes?

I have quite a few of these to do.

Please bear in mind that my max spindle speed (2,800) is an order of magnitude slower than ideal!

Cheers,

Steve
Advert

15 August 2022 at 18:01 #28804
Steve Crow
Participant
@stevecrow46066
15 August 2022 at 18:11 #609755
JasonB
Moderator
@jasonb
I don't think you could go much deeper with a 1mm cutter particularly when hand feeding which is hard to keep constant unless you like buying new cutters

A general rule of thumb is D/4 often a bit less on the very small dia cutters so your 0.3 is just over that.

Only thing that may speed it up a bit is switching to a 3-flute cutter which although I would use at teh same depth could be fed faster
16 August 2022 at 10:15 #609832
Steve Crow
Participant
@stevecrow46066
Thank you Jason , I thought I was at the limit with depth.

It is not a question of speeding things up – my thought is the less passes I have to make, the less chance of an error!

I have a CNC rotary table so I cut the hub and rim under power and hand feed for the spokes.
16 August 2022 at 10:38 #609835
Martin Kyte
Participant
@martinkyte99762
A freind of mine did his wheels that way on a Seig X1 CNC conversion. He used an engraving spindle (the type with a flexi drive and remote motor) mounted insted of the milling head. The cutter he used to favour were router type (more like a rotary burr). We use the same cutters on our PCB machine to rout out PCB's and they cut at a fair old rate. You could consider mounting such a spindle as an auxilliary to your mill offset from the mail spindle.

regards Martin
16 August 2022 at 10:56 #609842
Anonymous
For full width slotting my preferred milling cutter manufacturer recommends a maximum DOC of 0.5D for 6mm and over, and 0.2D for less than 6mm. For making a nameplate in 1mm thick engraving brass sheet I used a 1mm 3-flute carbide cutter with a stepdown of 0.2mm:

I ran at 24000rpm and a feedrate of 350mm/min.

For similar in steel I used a 0.5mm 3-flute carbide cutter, also running at 24000rpm, but 120mm/min feedrate. Depth of cut per pass was 0.05mm:

The original cutters came from Drill Service, but I broke two of them, both after about an hour of machining, so I was operating on the limit. A change to a cutter of the same spec but from Cutwel lasted the two hour machining time with no problems. So I suspect the 0.2D 'rule' tends to go awry for very small cutters (<1mm) and harder materials.

Andrew
16 August 2022 at 11:00 #609843
Steve Crow
Participant
@stevecrow46066
I have considered something similar Martin but mounting it would involve much butchery.

If I could find a flexi drive that would fit through my main spindle, that would be ideal.

Sherline do a pulley kit to increase spindle speed to 10,000 but the faff of changing pulleys every few days puts me off.

What sort of diameters are the cutters you mentioned and the depth of cut?

Steve
16 August 2022 at 11:06 #609846
Anonymous
Posted by Martin Kyte on 16/08/2022 10:38:42:

…mounted insted of the milling head.

I do something similar, but mounted in parallel with the main milling head, for small cutters on my CNC mill. The high speed spindle is mounted on the main spindle nose using a home made bracket:

Andrew
16 August 2022 at 11:15 #609848
Peter Cook 6
Participant
@petercook6
Posted by Steve Crow on 16/08/2022 11:00:24:

Sherline do a pulley kit to increase spindle speed to 10,000 but the faff of changing pulleys every few days puts me off.

Doesn't the Sherline High speed system have two concentric pulleys, so swapping from 10,000 max down to the other (2200 it seems to be) is just a question of shifting the belt on the pulley set rather than changing pulleys.
16 August 2022 at 11:33 #609852
Steve Crow
Participant
@stevecrow46066
Posted by Peter Cook 6 on 16/08/2022 11:15:52:

Posted by Steve Crow on 16/08/2022 11:00:24:

Sherline do a pulley kit to increase spindle speed to 10,000 but the faff of changing pulleys every few days puts me off.

Doesn't the Sherline High speed system have two concentric pulleys, so swapping from 10,000 max down to the other (2200 it seems to be) is just a question of shifting the belt on the pulley set rather than changing pulleys.

You're right, I hadn't noticed that!
Author

Posts