Mach AT problem?

[rmgreen]

I hooked up and operated for the first time a 850 rotary hand piece. This work with amazing ease and speed as to removal of background material. Previous to hooking up the 850 I was using a 901 AT with no problems. However, when I switched back over to the 901AT I could not get the 901 tuned. I get the vibration at low psi and as the psi is raised I get the hammering. I can not get the 901AT to stop hammering no matter what the air pressure setting is. I spent all Friday afternoon with tech at GRS and still the problem persist. It does not matter if the 901 is hooked up to AT position 1 or 2 both do not work. If I switch to foot control the 901 works perfectly. I have looked for pinched/holes in air supply lines inside and out and nothing found. I was hoping some one here might have a solution to this problem. Roger

 

[Brian Marshall]

Is the valve all the way SHUT that goes to the 850? You shouldn't leave it open when not using it.


Brian

 

[Sam]

Be sure that the handpiece 1 and 2 selector switch is all the way to the left or all the way to the right and not somewhere in between. Check the foot-hand selector switch as well.

Lower the air pressure to zero with the regulator knob and advance the pressure to tune the handpiece (I'm assuming you've done this already...repeat if necessary).

Be sure you have adequate pressure going TO the Gravermach AT from your air compressor.

 

[fegarex]

I am guessing the #1 #2 switch isn't all the way to either position as well.

 

[rmgreen]

I have tried with the GRS tech "Shane" all of these possibilities of why my Mack AT is not working and no change. We even took the little air tube white QC off for the AT hand piece and that made no difference which indicates there is no hole or problem with the lines going to the AT hand piece. The problem is some where before this point. I will try a little soapy water to try and find where any air leaks(bubbles) are. I am positive the Auxiliary Air(850 air supply) adjusting knob is complete off and that the hand piece selector switch is fully to station 1 or 2 and that the machine is properly set for the hand piece and not the foot pedal. My incoming air is 90psi with ample CFM (5hp - compressor) the Mach AT is set to 20psi and the tuning regulator will go up to 20psi and the hammering does not begin to change once it is at it loudest point. I have tired increasing the machines psi to 30psi but this does not make any difference either. The Mach AT worked for several years w/o problem as I only had the 1 hand piece and did not do much switching except from hand piece to foot pedal control for stippling. Tuned the hand piece many time during this time with no problems???? Thanks for your replies and if anyone comes up with another possible solution please let me know. I really do not want to send my Mach AT back to GRS. Roger

 

[Sam]

Shane knows the equipment inside much better than I do. I'm out of ideas.

 

[guzzi]

Check to make sure your 901 hose is fully engaged in the Quick Fitting. Remove the hose from the fitting, cut 1/4" off the end of the big hose, wipe the end across your forehead (body oil) and firmly reinsert in to the fitting, then pull back on the hose gently to insure a good tight fit. As Sam had suggested, the handpiece selector switch has a line on it to indicate port 1 or 2, this line must be parallel to your workbench. Usually a handpiece that runs on its own is a result of air leakage somewhere in the selector switch or a small hole in the handpiece air line, there is also a small o-ring in the selector switch that seals the air circuit, if you ran the regulator up over 50psi it is possible that the o-ring has blown out of the selector assembly. jb

 

[Sam]

Thanks again JB

 

[Brian Marshall]

Ah yes... the holes in the airline joke...!

I had that experience with my Airtact handpieces a coupla years back.

Spent weeks trying to figure that one out.

By pure accident, I sat down at it for the last time before I sent it back to the factory...


And guess what?


I felt a little air across my palm.


On further inspection - I found that BOTH handpiece airlines had several "pinholes" in 'em.


On further cogitation - and because the cause of the problem happened to walk into the shop -


I realized that I was the victim of a kittens joke... they have REALLY fine/sharp teeth.


You cannot see the holes they make....



Brian

 

[rmgreen]

Thanks to both Brian and "guzzi". No matter what there is an air leak as everyone has indicated the possibles. I do not have cat/kittens but the possibility of "holes" does exist. "guzzi" I will take the side off and see if I can see/hear/feel any air escaping. After checking again all of these things I will make a return call to Shane to try trouble shooting again with GRS. All of you have been very kind and I hope we can find the cause and a fix. Will post what/where the problem is/was so if others have this problem pop up there will be another solution. RmG

 

[DKanger]

Ah yes... the holes in the airline joke...!

Hmmmm, the cigarette burn in my air line must be part of my problem.