need help with antique centerless grinder

[recker]

i need help making a cone out of some 3/8 tube alum the cone is 1/2 deg off center 4.5in long and a 16 finish. i try to remove alum buildup on abrasssive wheel by following cam with dressing unit then readjusting the rest and finally adjusting the friction wheel,, but now the parts comeout chewed and gouged and it just doesnt sound right:'( but everything seems to be replaced in the same position as before. i have littel/no exp on any centerless machines and no one else that i talk to seems to know, to make matters worse the grinder is from mid 1950 and very tired. but it is operational.

any help would be usefull,

 

[unclesyd]

Grinding Al is a bear any way you look at it. I haven't seen any Al part that can wiggle be ground successfully. Your Al is gouging and welding back to the part.

As I understand your problem I would look at roll forming or spinning to get this shape.

 

[recker]

Actually it looks like the AL is being chewed off the part and deposited on the grind wheel.

as for the optional ways of production, they would take to long, because there are about 6 drilling and lathe operations prior to grinding. i need 700 parts in 30 mins .

do you know how the wheels should be shaped or what the blade and rest location might be in relation to the wheels

right know the blade and rest are at center and the wheels are cut to 1/2 degree

i didnt change very much to get such a distructive result
im sure its just something basic.

it is also the "infeed" type of setup, in that the part is inserted by hand the grind wheels pull the part to a stop and then the operator moves the regulating wheel in by hand to grinde the part to its final dimension, then pnumatic ejector to remove

 

[Greystone]

You might want to try a resin bond grinding wheel as opposed to a vitrified bond. Conventional centerless wheels are generally on the hard side, you might be having a heat problem. Resin bond wheels are cooler grinding and self dressing, this might eliminate some of the build up on the wheel. The only problem is, few suppliers carry these in stock,you might have to have it made. I would suggest sombody like Norton or Radiac.

 

[recker]

since my first post, I finaly figured it to be the angle that the grinding wheel had to be ground compared to the regulating wheel ( exact mirror of each other / \)

if the angle was off just a little bit it would make the part chatter and get hot fast.

i also adjusted gib a bunch.

it does use resin bond, but still after a while the finish willstart to get coarse and will need to be manually dressed, i guess due to the high volume of parts.

 

[sparkout]

Hey Recker,

Make sure your mirror image is also in your Workblade, also give the reg head about a half degree tilt to hold part to stop. Have had great success grinding aluminum using a60 grit plastic bonded wheel by Research Abrasives, also Perkins, acoolant mfg. here in Chicago area makes a great coolant for aluminum.

 

[recker]

thanks, ill be giving you a call.
im using hangsterfers for coolant,,, and the tilt on the regulating wheel was a large part of the problem. at some point it was moved to 3.5 deg and was jamming the part against the stop causing the part rotation to stall not seeing this because of the coolant shower over the part, i would then proceed process the part compounding the problem, i moved the regulating wheel to 1.5 deg(any less takes to long to pull the part to the stop)and the parts seem to feed alot smoother. my bigg problem now is dressing the wheel, it seems no matter how slow i go or lite i cut i get these little radial lines on my part ,i can see buildup on the work blade and i clean it off but still get these lines, how slow sholud i dress the wheel how deep of cut????????? it is a hydraulic unit on the grind wheel and manuual crank on the regulating wheel

 

[sparkout]

The deposits on blade we call "gauling", basically this is from to much heat at grind point and or pressure being applied on blade or the lack of lubricity in coolant, try to raise part height as far above center as possible without causing chatter, if this doesnt work, look into the lubricity issue. The coolant you are using is a highly rated coolant for steels, I've never personally used it for aluminum though.

 

[recker]

hey sparkout they took your contact info out of the post before i had a chance to get a hold of it, can u repost?


how should the grind wheel be dressed ??
depth of cut , feed speed Etc.
should work blade be elevated on one side when grinding a tapered part?
how should the blade be positioned in t