Numatx squeezer set up

[Jskyking]

Today, I set up my squeezer. It?s not squeezing-4 or -3 rivets to the proper compression length.
- I bled the system three times to ensure no air was in the lines, disconnecting the clear plastic (A,B, and P) at the ports. I set the c-squeezer in a vise to ensure the bleed port was at the highest point of the system.
- I kept the black hyd hose nearly flat to prevent sag and possible trapped air
- checked all the fittings,
- adjusted the air pressure to 74 psi (-4?s) and 44 psi for the -3?s
- topped off the intensifier at the bleeder
- Teflon taped the set screw in the c-squeezer bleeder
- using dextrin 111
The squeezer closes and slightly squeezes the rivets but nowhere near compression specs. I don?t have any air leaks.
Hoping that someone else has had a similar problem and can shed light on this issue.
Thanks
Jt

[Stockmanreef]

so you don't adjust the piston? Maybe new ones are different. Mine runs at 95 psi. I adjust the length of the piston travel. It screws in and out. Yours just works on pressure?

For dimpling, I make sure that I see the yoke or c-frame flex when setting the dimples.

[Jskyking]

Isolated the problem- Harbor Freight junk regulator. Numatx squeezes like a champ after taking the regulator out of the system and going with Speedaire regulated shop air.

[jwellman]

> Yours just works on pressure?

Yes, the Numatx squeezer works on pressure vs ram length. It is a hydro-pneumatic squeezer where the "typical" squeezer is just pneumatic.

It's an excellent tool, but requires pretty precise control of air pressure. You can squeeze rivets of different length without making any adjustment.

http://rv10.blog/2019/02/24/new-sque...d-shop-vacuum/

Jared

[Stockmanreef]

Interesting. My Numatx is from 2013, so it works off adjusting the ram length. With that said, I am not actually sure that it would not work the same way. I just keep mine adjusted to 95 psi and adjust the ram length. Maybe it would work the same way as yours. I will try sometime when I am out in the shop.

If I had that the new squeezer, then I would have two regulator permanently setup at the two pressures.

[ROTARY7]

Jared is correct. There is no cam mechanism (lever principle) in the Numatx squeezer, it works simply off hydraulic pressure. Doubling the air pressure into the intensifier doubles the hydraulic pressure, thus the force. Force = Pressure x area (piston area). I can teach someone to squeeze a rivet correctly when they do not know the air pressure to achieve the correctly formed head, simply by "sneaking up" on the rivet with a very low pressure. Start at 20 psi, then 25 psi, then 30... Very quickly the correct "pressure" (regardless of how accurate the user's gauge is) can be determined, using the .5-.6D height rule for rivets per FAA AC43.13. If it sounds complicated it is not. It is simply quick trials to find what works.

Ken is also correct about the threaded compression pin he has. His unit was an earlier version that I designed that did have a threaded compression pin for coarse adjustment. The problem was that some users were unthreading the pin too far, and did not have enough threads in engagement to carry the 3,000 pounds of force during squeezing, and would damage the threads. So, I simplified the design and removed the threaded compression pin.

Since the Numatx unit has constant force (force along any part of the .55" stroke is the same), it works a little differently than a traditional pneumatic only unit and is not really needed. As others have said, a -4,-6 or -8 rivet of the same material and diameter can be squeezed without any length (die) adjustment. This is a further advantage of the Numatx unit besides being smaller and lighter.

You can also set rivets by adjusting the length of the compression pin with shims, die lengths and so forth, the same as traditional squeezers. But why bother, when you can simply dial up or down the pressure regulator.

Ken also makes a good point: Get two air regulators, and use a two way isolation valve prior to a Y of the two valves (McMaster-Carr or other source). Then you can simply flick an air valve to go with whatever two pressures work for you and 3/32 and 1/8 rivets.

[FlyGuy65]

Do you have any insight on the 60 PSI minimum limitation listed in the manual (or am I misreading something)?

[ROTARY7]

Yes, you didn't misread the 60 psi limitation, it is a mistake in the manual. Numatx units can be readily operated below 60 psi, and of course need to be operated at about 45 psi to squeeze the abundance of 3/32" AD rivets in RV kits. Hy-Tech Engineering put 60 psi in the manual, despite my objections, as HT has had some customers with commercial units trying to use too low of a pressure (~10-20 psi) to develop lower force. In these cases the units operated very slowly. But for the 3K systems people are using for light aircraft construction, 35 psi is about the lowest pressure needed to squeeze a 3/32" rivet, and the operating speed is just fine.

[TS Flightlines]

Mark did the originals. I have one---well the guys at the airport are 'borrowing' it. Worked flawlessly for me, and I'm NOT a structures guy! WE did make a coulple of special dies for colse tollerances like ribs and angles.

Perhaps the new versions are different. Dont know. Mark can tell us---
Tom

[tdavis1198]

I am about to return mine. The travel distance of the pin is very small. About 1/4?. I called the company and they said send it back and implied that they have seen this problem before. Does anyone know anything about this issue?