sprayhead
Thu 22 October 2009, 00:15
Hi,
I have made some tests with a mod. 4, 13 tooth, 52mm pitch diameter, AISI1045 steel, black oxide finished pinion and a Nylon rack.
The test consisted of myself grabing the pinion by hand and rolling it over the rack forward and back while applying different pressures on the pinion against the rack. Guestimation tells that I have applied 5-15 kilos of pressure on the pinion. Since I was using a shaft through the pinion, it was easy to push it down against the rack.
The primary conclusion is that it runs very smooth and quiet, and it definitely improves as the pinion and rack further adjust. I was impressed. For some reason I thought that it was going to run rough and "vibrate" going up and down.
The rack costs only 25 bucks for 1000mm lengths and the pinion only about 5 dollars each, ordered straight from a factory in china. The rack is made of nylon, injection moulded, it has an internal steel flat bar running length wise for reinforcing and the quality looks nothing short of good. I did not test for pitch discrepance over lenght but I guess that if the mould was properly designed it wont be a problem.
I did extensively try to get a smaller modulus rack with but at this price I couldn't find anything but modulus 4.
If anyone is interested in giving it a try, let me know, I am just about to order 20 pinions.
The rack is very easy to find... It's made for gate automation. The particular rack that I have used was designed here in Australia.
Francis
I have made some tests with a mod. 4, 13 tooth, 52mm pitch diameter, AISI1045 steel, black oxide finished pinion and a Nylon rack.
The test consisted of myself grabing the pinion by hand and rolling it over the rack forward and back while applying different pressures on the pinion against the rack. Guestimation tells that I have applied 5-15 kilos of pressure on the pinion. Since I was using a shaft through the pinion, it was easy to push it down against the rack.
The primary conclusion is that it runs very smooth and quiet, and it definitely improves as the pinion and rack further adjust. I was impressed. For some reason I thought that it was going to run rough and "vibrate" going up and down.
The rack costs only 25 bucks for 1000mm lengths and the pinion only about 5 dollars each, ordered straight from a factory in china. The rack is made of nylon, injection moulded, it has an internal steel flat bar running length wise for reinforcing and the quality looks nothing short of good. I did not test for pitch discrepance over lenght but I guess that if the mould was properly designed it wont be a problem.
I did extensively try to get a smaller modulus rack with but at this price I couldn't find anything but modulus 4.
If anyone is interested in giving it a try, let me know, I am just about to order 20 pinions.
The rack is very easy to find... It's made for gate automation. The particular rack that I have used was designed here in Australia.
Francis