Grs foot pedal hack?

[Chujybear]

I remember reading about a little hack that somebody (who I am used to seeing in this forum) had developed, that was supposed to make the pedal more responsive.. I'm not being purposely cryptic, I actually can't put my finger on which member it was.
I might be out of luck here, because I also have a vague recollection that it might have been for the graveneister...
I am running a gravermach with my spm'sturned down, and the air up, with the large hammer piece in to do a little chasing. And, I am noticing that the air doesn't kick in till the pedal is half depressed..
Any insight would be appreciated..
Thank you

 

[Sam]

I believe that's Mitch Moschetti who has a foot pedal mod.

If your pedal is depressed half way before the handpiece starts to stroke, it usually indicates too much air pressure. Set the air pressure to zero and hold the handpiece upright in your left hand and increase the air pressure. You should feel the handpiece start to flutter and then start to tap. If you get no response then lightly depress the foot pedal. Continue to increase the pressure just until it stops tapping. If you overpressure you'll have to depress the foot pedal too far. If you do it correctly, as soon as you touch the foot pedal you get a clean, sharp tap of the piston. You want to be right on that threshold, not over pressured. If you're under pressured, the handpiece will vibrate and flutter before it taps. This might sound complicated but in reality it's takes just a second to set the air pressure correctly.

 

[Chujybear]

No. Perfect sense.
Don't think I mentioned it above, but I cranked the pressure. Thinking, I guess, that that would punch up the power.
Thanks

 

[Sam]

Yes, I read that you had the "air up". You don't crank the pressure to regulate the power. You adjust the regulator so as soon as the foot pedal is touched it starts to tap cleanly and sharply without vibration or flutter. You're not the first person who thought increasing air pressure would increase power, when in fact it does just the opposite.

 

[Jeroen]

Hallo Chujybear

Maybe you were thinking of Chris DeCamillis' Throttle Command Module?
http://www.engraversstudio.com/apps/webstore/products/show/1930542

Jeroen

 

[Chujybear]

That might be it. Looks handy. And would suite the switching of handpieces that I have been doing

 

[Sandy]

Sam,
Do you set the air pressure at the compressor or the control box.
Sandy

 

[blacksmith_wills]

Sandy,

Set the pressure for the handpiece on the front of the Gravermach.
Regards,

Matt

 

[Sam]

Yep. On the front of the machine.

 

[mitch]

Wow- i've been out of town for a week and while i was away i got promoted to "hack". cool! how many more of these upgrades before i get to claim official status as a "master engraver"?

without getting into another lengthy discussion on how the gravermax system works in general, and the throttle in particular (that thread is in here somewhere if you search for it), yes, i did come up with a way to adapt a throttle control valve to gravermaxes/machs/smiths that don't have the 'bias valve' of some the newer units. i also included instructions for adjusting the bleed valve in the foot pedal so that the new valve controls the initial necessary 'leakage' in the system and lets the pedal use the very finest part of its range.

in the time since i came out with this aftermarket mod, i've really become a student of how all this stuff actually works. a couple key things i've learned:
1) a given handpiece, piston, & spring combination will run at essentially ONE given air pressure level. trying to crank up the air for more impact power only means you'll be pushing the pedal farther before you've bled off enough air to get it back down to its natural operating pressure. in other words Chujybear (if that IS your real name...), you're kinda creating your own problem.
2) a perfectly tuned machine/throttle/pressure combination is an ever moving target. as an experiment, i've installed a precision regulator and a 1.5 liter accumulator tank ahead of my gravermax, and have a big, fairly cool-running 4-head Jun-Air compressor. in theory, the volume & pressure to my unit should be about as consistent as possible without resorting to some sort of astrophysics lab type of equipment. i find i STILL end up tweaking things with my Throttle Command Module (like Jeroen posted above*) throughout the work day. as far as i can determine, this is largely due to heating & cooling of the handpiece- from internal friction of the piston, external heat from my hand, & fluctuations in the temperature of the supply air as the compressor warms up and the ambient temp of my shop changes, etc. for bigger, coarser cuts i can safely ignore this phenomenon, but for finer work i do make occasional throttle adjustments with my TCM.

*having said all that, i've recently decided to discontinue manufacturing these things. the main problem is having to special order the valves in a quantity sufficient to get a decent wholesale price, then it takes months to sell that many finished units and recoup my significant upfront investment for each production run. if orders keep trickling in i may decide to offer them on a back-ordered waiting list basis. when enough orders pile up, i'll make more. we'll see....

 

[Chujybear]

Thanks for the in depth answer. I guess I went back to work, missed the big explain right from the horses mouth.
Not that I'm calling anyone a horse (or did I just) , or a hack , for that matter.
Much appreciation for taking the time.
And chujybear is not my real name... Tho the real one would prolly sound no less strange

 

[Arnaud Van Tilburgh]

Mitch, I have one of your TMC ones connected to my GraverSmith and tuned the pedal like you explained in the manual. Still satisfied with it.

arnaud