Thread: Etch Press Build
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17-05-2018 #1
Hi all,
Just wondering if anyone has any experience with building an etch press - something along the lines of this:
I've started to design one and have begun collecting odds and sods that I'll be using along the way (take-up bearings, flange bearings etc.)
One thing that's got me a bit stumped, though, is how to get my hands on a pair of live shaft stainless rollers. I'm attaching a .pdf of what it is I'm after. Dimensions are approximate at the moment, but won't be far off that. The long 60mm shaft will need a flat on it for the hand-wheel grub-screw to bite on.
Ok, there's the obvious way, pay someone to turn 'em - I imagine this will be pretty pricey, given the chunkiness of what I'm after, but if you know any different then let me know..!
Or I could fabricate 'em from a steel pipe with a steel shaft passing through it held central by a couple of alu caps made on the mini-mill. (All probably glued up with the strongest epoxy I can find...)
Any other ideas..?
Wal.
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18-05-2018 #2
Even with a lathe I'd be temped to centre drill stock 50mm stainless bar pre-cut to length, bore out (or drill) then ream to 15mm dia and maybe 40mm depth, then tap some 15mm dowel into the reamed holes with some loctite.
I wouldn't bother trying to turn down the 50mm bar. At least with my ML7 (small spindle bore) I'd have to turn between centres.
I guess there's a reason it has to be stainless?
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18-05-2018 #3
Having just read a bit more on the topic, the drive roller would be fine in 7075T6 with the idler in mild steel - had stainless in mind as it's what (little) I remember from the college art room... The crucial bit is that the rollers run absolutely parallel to each other (this can be tweaked via the take-up bearings) and that the running gear can withstand high pressures.
I may well have to consider increasing the shaft diameter to a more substantial 20mm and have a closer look at using self-aligning bearings to accommodate said tweakage... This could get a bit pricey...
Wal.
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18-05-2018 #4
Hi Wal,
This build uses tube for the rollers
https://www.youtube.com/watch?v=UhlSZU63S7g
and these for the pressure adjustment
http://www.arceurotrade.co.uk/Catalo.../Take-up-Units
Interesting project, but not for me (too many projects stalled on the bench )
Cheers, Rob
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18-05-2018 #5
Cheers Rob - that clip makes it look too easy..!
Wal.
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18-05-2018 #6
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18-05-2018 #7
If you could find an old number plate machine you'd have no work to do, they're effectively a heavy duty mangle with geared steel rollers.
You think that's too expensive? You're not a Model Engineer are you? :D
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18-05-2018 #8
Hi Wal,
Don't know if this could be what you need but I have a 610mm x 50mm dia with a 30mm bore through it Stainless steel rod, I also have a piece of 465mm x 32mm dia solid stainless bar which would turn down for the ends.
All you would need then is someone with a large enough lathe to turn down the ends to fit into the tube then skim off true the tube and away you go, easy!
Phill
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18-05-2018 #9
Hiya Phil,
Thanks very much for the heads-up on those materials.
I think I'm leaning more towards the 'one-piece' solution as it'll probably end up easier communicating what it is I need doing to a shop (and will result in fewer steps for them to take to get it made). From a strength point of view: these rollers need to take around 40Kpsi - I'm guessing that by sliding the shaft through the middle like that you'd be talking about a fairly substantial non-slip interference fit along the length of the roller - not sure what kind of stresses that would introduce and how they'd interact with additional stresses that the printing process will put 'em through...
Wal.
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21-05-2018 #10
Still doing my research on this (materials, why some have a spring under the take up bearing etc.) but this is how the design is shaping up so far...
Wal.
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