Center less grinding

[Jasonmissimer]

Anyone have any knowledge of center less grinding out there..having a issue with "grind lines" in finished parts..grinding on a 5 head Acme abrasive belt grinder. Grinding a carbon steel tube from a 7/8 dia to a 1 1/4 dia...alignment seems to be right..good run line on carbide tipped blades..no rattling while parts are running thru machine..I can't figure it out..I'm stumped

 

[EdStainless]

What do they look like?
Which direction, how long, how wide?

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P.E. Metallurgy, Plymouth Tube

 

[Jasonmissimer]

They are only half way around the tube so maybe 1" or so long..evenly spaced apart about 1/16 of an inch..but they only appear in sections of the tube..I have removed all side guides and have taken out carbide tipped blades on the last 3 finishing heads and replaced with brass..it's hard to pin point because it is not on every tube..might be on 1 and then the next three will be ok..then the next two will be ok and so on...all my coolant levels are where there are souposed to be..I will take a picture of them tomorrow when I get in to work and see if that helps

 

[Jasonmissimer]

Also I have checked and rechecked the alignment of machine numerous times

 

[EdStainless]

OK, let's look at this.
What abrasive lineup are you running? (grit progression)
It really sounds like you either have some bouncing or slip.
How is pressure controlled on this machine?
What are the regulating wheels? (material and shape)

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P.E. Metallurgy, Plymouth Tube