Fingers crossed it'll cut ally

[Jonathan]

It's only messy if you machine through the tape.

It is the number one method used for holding down small flat thin components.

I've used it on countless occasions at school with the small Roland PNC2300 engraver.
It doesn't leave a mess iff you get the right tape...found that out the hard way :(


I don't like the sound of blu tack - difficult to get it level! More environmentally friendly though I guess.

[blackburn mark]

Well I've never heard of that method. You must like doing things the hard way lol

what are you like phil ? ... if there was a vice handy or a vacuum bed or a t-nut............. no, there was a lovely peice of blu-tac just sitting there looking at me :) so i used that and got on with my day

[blackburn mark]

difficult to get it level

hi jonathan, i used the bottom of my Z to press it level :) when iv used it on the lathe face plate i did the same again but with the stock,,, where theres a will :)

Edit: dont try this at home unless you have the magic spell off Gandalf !!!!

[Jonathan]

when iv used it on the lathe face plate i did the same again but with the stock,,, where theres a will :)

Wait. Did I read that right, you attached something to the lathe using blu-tack!! That sounds a bit dangerous, even by my 'accident waiting to happen standards' :lol: I guess if you went really slow, but surely blu tack wouldn't take the cutting force...

I do like the look of your vacuum thingy. Where do you get the valves?

[blackburn mark]

even by my 'accident waiting to happen standards' :lol:

yep ! even by your crazy arsed standards :)
i made a nema23 stepper motor mount out of delrin... i didnt have the swing to use a normal chuck but with the face plate i could just squeese the bugger in........ the art of engineering :)
thats why you dont get any saftey tips from me jonathan, dont get me wrong, your fingers are well useful so dont go losing any however somtimes you have just got to go for glory and keep the buggers crossed

[blackburn mark]

I do like the look of your vacuum thingy. Where do you get the valves?

nice one jonathan, i was starting to think i was on my own with this one

they are fish tank check valves 10 for £3 ... bargain ebay :)
i havnt tested these ones yet but they do the same job as the one iv already got
(fingers crossed they will hold a vacuum without collapsing the diaphragm) ill let you know.
get the transparent ones, they may indicaite to some exstent the state of the vacuum
let me know if you want a syringe ill send you one across

[blackburn mark]

some developments :) another 4 pads to make and im ready to give them a try

its probably wise to keep the lose air to a minimum, small bore pipes etc that way you can pull a harder vacuum
i will be using a one way valve between each pad and the manifold (makes sense if you think about it)
iv oppted for the 35mm o-ring size for now they have a good holding force but not enough to bend/warp 2mm alli (i think) i may make some 60mm pads for heavier material cutting if these work out well
the glue im using is the heat type, iv had no leaks so far :)
you could use two o-rings (one smaller and inside the other) to clamp over holes
you could make up some exelent kits with this stuff
but we will see when it comes time to do some cutting on them

[Jonathan]

Interesting stuff. You could stick a sheet of whatever plastic you're using down to the bed and mill slots/holes for the air ... then flip it over and cut out a grid of rings to fit your O-rings. Might be worth thinking about what pattern of rings would hold things best - some bigger than others? Could have rectangular ones, all sorts!

I might have a go at this, got some 6mm acrylic that would do the trick. Got plenty of O rings from £1 shop. Some might be big enough.

With a sufficiently big syringe how many pads do you think could be served? Or are you sucking the air out of one at a time and swapping the syringe round?

I'm looking at the servo controller now. I've traced the PCB and drawn circuit diagram of the interesting bits. The problem is the one you sent me has one significant difference to yours - mine gets 3.3v for the microcontroller and potentiometer via a 3.3v voltage regulator. I think yours is either a 5v microcontroller, or they're getting 3.3v via a voltage divider....

Could you measure the maximum voltage from between R32 and ground on the PCB please? I may have asked you to do that already, this thread is so long I'm not sure!
Also what resistance is your potentiometer - it says on the metal case (FB5k ... i.e 5k ohms for mine)?

Edit: don't worry about the voltage, post #90! Except was that definitely the voltage from the resistor to ground, not across the resistor?

[blackburn mark]

You could stick a sheet of whatever plastic you're using down to the bed and mill slots/holes for the air

iv considered it for long runs, might be a pain to get the holes routed to each o-ring if its a complex pattern

the problem with mixing diffrent size o-rings is the diffrent surface arias would compress the o-rings diffrent amounts

With a sufficiently big syringe how many pads do you think could be served? Or are you sucking the air out of one at a time and swapping the syringe round?

im going to try using one syringe and fix one of the one way valves as an exsaust so you could pull the initial vacuum the pad valves will hold the vacuum ill press the syringe home and the air iv removed from the pads will be routed through the exsaust one way valve ?????? if you can get your head around that :)

i need to do a drawing to show you what i mean.... imagine you have two one way valves attached to the end of the syringe, youll work it out :)

am i sending you a large syringe ? (iv got a few from work)

[Jonathan]

imagine you have two one way valves attached to the end of the syringe, youll work it out :)

am i sending you a large syringe ? (iv got a few from work)

Oh, two valves ... you're using the syringe as a pump!
If you could send me a syringe that would be great, I've not got any that seal any more - found out they don't like concentrated sulfuric acid. I can papal you something for it.

I had better buy some valves and tube. What diameter are you using?