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View Full Version : CNC job request for quote/interest - an enthusiast project, not commercial



jhovel
20th Jan 2021, 01:57 AM
Anyone here interested in a project and/or a quote?
It's an almost 2D job but with draft. Its a flat hot press tool for a collaborative project for a small band of enthusiast....
Around 200x65mm and 6mm deep relief with 10 degrees draft.
I had hoped to get my desktop CNC mill going to do this but other things have taken priority and the learning curve keeps me form getting very far at the moment....
This is what it needs to look like and I have the Fusion 360 file ready to go.
390452

Michael G
20th Jan 2021, 07:30 AM
That's not going to play nicely for CNC (or any vertical milling really). There are sharp internal corners and the spacing between the letters is pretty small in some places. 10 degreee cutters are available (I have a 3 degree I bought from the US, but other angles exist). How deep are the letters?

Michael

jhovel
20th Jan 2021, 03:29 PM
You may be right, Michael. I'll see what we can come up with. I have a few 10 deg D-bit cutters with a few thou flat on the end that may do it. Alternatively, I could reduce the draft angle to closer to vertical - maybe 3 degrees or so. The reason I chose 10 deg. is to ensure even heating of the tool at the surface, because the letter outlines are effectively 'cooling fins'...

Just for the curious: this is what it's intended to do. It's the seat cover of a Honda CX650Turbo for the European delivered ones only (very small number). They are all now 40 years old and cracking. Nobody makes replacements, so I started a collaboration with a seat cover maker in Thailand and an owners' group in Germany to get a few replicas made.
390457

pippin88
20th Jan 2021, 05:24 PM
Material?

Michael G
20th Jan 2021, 06:25 PM
Just thinking out loud here Joe -

The impression on the vinyl is not deep, and the letters are solid.
If you had access to a fret saw, could you put the table over on a slight angle (optional really) and then cut the letters out of say 1mm thick copper using a stuck on paper template, then braze/ solder those cut out letters onto a steel block*. The steel could be potentially relieved in the middle of the letters, but would probably stamp the surface of the vinyl well enough as I would imagine it only needs to be 100 to 150 degrees (after all, you are only taking the pattern off the vinyl, not melting it).

Michael

*You could keep the letters aligned with tags to the sheet that could be milled off later

elanjacobs
20th Jan 2021, 07:23 PM
That's not going to play nicely for CNC (or any vertical milling really). There are sharp internal corners and the spacing between the letters is pretty small in some places. 10 degreee cutters are available (I have a 3 degree I bought from the US, but other angles exist). How deep are the letters?

Michael
Reduce the depth to 2-3mm, it doesn't need to be milled out to 6mm for what you're doing. Back when I was making furniture, we had some branding irons made up in solid brass with MUCH finer detail (sub-mm line thickness and spacing with sharp internal corners), so I see no reason it can't be done; you just need to ramp in Z to get the sharp internal corners.

BaronJ
20th Jan 2021, 10:34 PM
Hi Joe, Guys,

Many years ago I had a stamp made from lead type by a friend of mine that had a printing business. He made the lead type on his "Linotype" machine. I used it for stamping the company logo into PVC product caps, mainly to stop another company from pirating the product, which it did very effectively.

The type was mounted on a heated brass block and pressed onto the cap to emboss it. The temperature had to be carefully set and controlled or the stamp stuck to the PVC cap. I also used it to emboss the cardboard boxes used to pack the products.

Fun times ! :U

jhovel
21st Jan 2021, 04:46 PM
Material?

Aluminium - any grade will be fine.

jhovel
21st Jan 2021, 04:49 PM
Reduce the depth to 2-3mm, it doesn't need to be milled out to 6mm for what you're doing. Back when I was making furniture, we had some branding irons made up in solid brass with MUCH finer detail (sub-mm line thickness and spacing with sharp internal corners), so I see no reason it can't be done; you just need to ramp in Z to get the sharp internal corners.

Reducing the depth to 3mm should work. The pressing is done with a thin layer of foam behind the vinyl, so quite flexible. But 3mm deep relief should be OK. We don't want to melt the vinyl on the flanks of the lettering.... That's why I chose 6mm. But you are right, it may make it easier to mill with less depth.

jhovel
21st Jan 2021, 04:52 PM
Just thinking out loud here Joe -

The impression on the vinyl is not deep, and the letters are solid.
If you had access to a fret saw, could you put the table over on a slight angle (optional really) and then cut the letters out of say 1mm thick copper using a stuck on paper template, then braze/ solder those cut out letters onto a steel block*. The steel could be potentially relieved in the middle of the letters, but would probably stamp the surface of the vinyl well enough as I would imagine it only needs to be 100 to 150 degrees (after all, you are only taking the pattern off the vinyl, not melting it).

Michael

*You could keep the letters aligned with tags to the sheet that could be milled off later

Thanks fr the suggestions Michael. The letters are actually no solid - they are outline fonts and the impressions are only a mm or less wide... but keep ideas coming....

elanjacobs
21st Jan 2021, 07:30 PM
Aluminium - any grade will be fine.
I would suggest brass. Aluminium will lose heat quickly and so will be harder to keep at a stable temperature; commercial branding irons are brass for a reason.

Reducing the depth to 3mm should work. The pressing is done with a thin layer of foam behind the vinyl, so quite flexible. But 3mm deep relief should be OK. We don't want to melt the vinyl on the flanks of the lettering....

Stupid question... Why can't you brand the vinyl before the foam goes on? Or does it come with the foam already there?

jhovel
28th Jan 2021, 06:40 PM
Still experimenting with set ups using aluminium tread plate as a press tool. Trying different temperatures and process. Looks like 130° is the ideal temperature. Leaving the foam off works better.
I've made a new 3D model with less letter height and no draft. I think that will work ok. Doing it in brass might also help with milling with smaller cutters for smaller internal radii...

Cheers
Joe

Michael G
29th Jan 2021, 06:33 AM
Gee Joe, if only you knew someone with a copy mill you could use the 3D printed version to act as a pattern for something in brass :U

Michael

jhovel
31st Jan 2021, 11:02 PM
Yes, Michael.... :) Come to think of it, I do know someone with a pantograph router. But since the job is 200mm across, the pattern would need to be at least 1.4 times as big. That just puts it out of the envelope. Making the pattern 1.4 times smaller would introduce too much and too visible waviness in the final tool.... Don't think I hadn't considered that.

aarggh
1st Feb 2021, 08:36 PM
There's also plenty of metal 3d printers online you could simply upload the STL or model to and have it printed. Metal printing has really come down in price, and is very affordable now.

As Elan said, brass would be the far better choice material, and will machine far better than aluminium on most hobby machines without a mister, but it also work hardens which can be a problem.

I had to get some fly press stamps made not long back, and ended up getting them from the US as I couldn't find a local supplier that could produce what I was after. Seems really hard to find local places to produce stuff like this at prices that aren't unobtanium.