Thread: Fingers crossed it'll cut ally
12-01-2011 #171I can papal you something for it.
found out they don't like concentrated sulfuric acid
i didnt manage to get much of the surgical tubing, i need to buy some more myself, it looks like 1.5 or 2mm ID and the brass tubing is 3mm
i just used what i had lying around, if i was buying id go for the smallest diameter i could get
Ps: the only reason you would need to use the syringe like a pump is if it failed to seal on the first draw, it would save you having to remove the syringe and start again, im pretty sure you could pull a pretty good vacuum on 4 double sided pads all in one stroke
the 30mm pad held onto a un-polished block of alli for hours without the need for a top up, id top up every now and again if it was on the cnc though :)
12-01-2011 #172I'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?
this thread is getting a bit long i guess i should have split it up into spindles router and vacuum stuff
If you just measure the voltage at the point I said earlier. Remove that resistor (R32), remove R31 and connect the parallel port pin to where R31 connected to the potentiometer, then set spindle in mach3 to highest, adjust the pot so you get the same voltage as measured at R32 earlier. Put R32 back in place and do not move the potentiometer ever again otherwise the microcontroller will probably break.
Measure that voltage, if it's ok then I'll scribble a diagram over the picture you posted.
It would be good if a moderator could split this thread up to save duplication? If not then I'll start a new one about the spindles.
Just a note to say that the different size O-rings should all compress the same amount as long as they are all the of the same thickness, therein lies the problem getting the same thickness in different diameters.
Your right it is to good to be true, must have been asleeop when I did the calcs!!
12-01-2011 #178Your right it is to good to be true, must have been asleeop when I did the calcs!!
Yes Thats what you get when making quick calcs on the back of a fag packet while doing something else!
Took some time to find my error in th calcs!
Oh well seemed right at the time.
On some vac tables they have a cross hatch of grooves that you run a length of rubber around so its under the piece you want to hold and cut of any excess, can also be fitted with stops for repeat parts.
i've done some testing with these vacuum pads up to 50mm, they will work fine for engraving or fine cuts however due to the tiny footprint of the stiff o-rings the friction is a little low and there is the risk of the part slipping latteraly
jonathan, i've sent you a couple of syringes some tube (i found some more) and a one way valve, the valve is a medical job and it takes quite a bit of pressure before the seal is broken and it allows any flow so it needs to be mounted on the tip of the syringe to reduce pressure backlash, not perfect but it will give you something to experiment with, i'm leaning towards your idea of making a bolt down board unless i can find better seals, car oil filter seals might be much better for individual pads, they have a square section and a much larger contact area
i've sent it to your uni address
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