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Please recomend a polishing solution.. wheel?

pcm81

Cast Iron
Joined
Apr 10, 2014
Location
USA FL
I have a 3/4HP buffer and a belt sander. This combination works great when i can smooth steel part with belt sander first, up to 400 grit and then let the buffer take over. I am having a difficulty buffing concave geometries that i can not do on my belt sander. I can use a medium hardness wheel on the buffer and it will "flow" into concave geometry, however even the black emery is not able to remove the grind marks. Can anyone suggest a better wheel/compound combination? I also tried a hard wheel, stitched almost to the edge and that also was unable to remove grind marks from the concave geometry (curved chisel) i am trying to polish.

Thanks ahead
 
If you can do it by hand - then the foam backed sandpaper will work. Work thru the grits same as with your belt sander.
 
If you can do it by hand - then the foam backed sandpaper will work. Work thru the grits same as with your belt sander.

Trying to avoid doing it by hand, too much work. So far have been doing all of polishing (up to 0.05 micron diamond paste) by hand, trying to find automated solution, hence the buffer purshase.
 
The rigid highly compressed scotch brite wheels are what you want, Norton do a blue one (vortex rapid blend) and its the dogs bollocks on going from a rough machined - coarse grind to a finish that buffing only takes moments to get shiny they seam to hold up better than any of the 3m equivalents i have tried too.

For a concave surface you can dress the wheels edge to a approximate curve and they work well. There not cheap, but then on a time versus cost they make good sense on what im using them on and i would not hesitate to try them for what your doing.
 
The rigid highly compressed scotch brite wheels are what you want, Norton do a blue one (vortex rapid blend) and its the dogs bollocks on going from a rough machined - coarse grind to a finish that buffing only takes moments to get shiny they seam to hold up better than any of the 3m equivalents i have tried too.

For a concave surface you can dress the wheels edge to a approximate curve and they work well. There not cheap, but then on a time versus cost they make good sense on what im using them on and i would not hesitate to try them for what your doing.

Thanks, I'll give one a try.
 
For inside concave surfaces sanding/polishing I am using a Oscillating Spindle Sander. Comes with a wide range of cylinders and I can use either sanding sleeves or hard felt sleeves.
 
After a little more research looks like 3M bristle brushes is what I need. But looks like they are mostly intended for mounting it in a drill... Havn't seen any for 5/8th inch arbour...
 
^ Tried em, nah you want my previous suggestion, the bristles really do not do as well as you think they would and there expensive. you use to be able to get them for spindle mounting and also for rolloc screw on as well. But can't stress enough i found them pretty disappointing and never really did find anything they did better than something else.
 
I've found the coarser two or three grades of 3M bristle brushes good for removing paint and surface coatings, maybe up to medium mill scale if it's not too tight. Not the only thing on my shelves for those jobs, though. Definitely not what I would choose in a smooth/pre-buff situation.
 
After a little more research looks like 3M bristle brushes is what I need. But looks like they are mostly intended for mounting it in a drill... Havn't seen any for 5/8th inch arbour...
I only have two types: 5/8-11 arbor mount and RolLoc quick mount. So the 5/8 arbor versions do/did exist...
 
I've found the coarser two or three grades of 3M bristle brushes good for removing paint and surface coatings, maybe up to medium mill scale if it's not too tight. Not the only thing on my shelves for those jobs, though. Definitely not what I would choose in a smooth/pre-buff situation.

I tried them on both of thoes, these days paint removal here is handled by crushed glass blasting, its so damn fast and you don’t have to care about the abrasive getting loaded! I found the bristly brushes just tended to melt and mash paint around, not really take it off. I tried the coarse purple ones on rust and just found they wore down fast, do to cost again to me they just don’t really fill any niche i have found, something else does it better - faster. Im sure i can recall seeing videos of them being using on jet turbine type parts for surface smoothing, again they may work well on the right material, but really would not expect them to be the fastest or most economical approach for what the op is trying to achieve.
 
Thanks all for the replies. I read them all. I purchased the 6" bristle wheel to give it a try. Also am on a look out for the scotch bright wheels suggested above. After some youtube research i would agree that scotch bright wheel would do the job in terms of grit and quality of finish, however all the scotch bright wheels I saw were rigid and I don't think they would "flow" into the geometries i am trying to polish. Meanwhile, I can use the belt sander for easy to access places... its the concave geometries that I am after in this post.
 
Okay, I got to ask are these knife blades you're trying to polish. Either way, You will not get what you're looking for coming from a 400 grit belt and one buffing wheel/compound. I recommend going to 600 grit and with a set up of 3-4 different wheels and compounds, one could have a mirror polish on the part in a couple min. If you want a killer buffing system that has been tunned over the last 20 years give RW Wilson a call. He has custom buffing wheels made and compound. That said you would need another buffer. One 3600 rpm and one 1800 rpm.
 
Okay, I got to ask are these knife blades you're trying to polish. Either way, You will not get what you're looking for coming from a 400 grit belt and one buffing wheel/compound. I recommend going to 600 grit and with a set up of 3-4 different wheels and compounds, one could have a mirror polish on the part in a couple min. If you want a killer buffing system that has been tunned over the last 20 years give RW Wilson a call. He has custom buffing wheels made and compound. That said you would need another buffer. One 3600 rpm and one 1800 rpm.

General purpose buffing, not knives specifically, but knives are also part of the mix.

So far I tried the 80-grit 6" 3M Bristle disk Brush and I like it. Also picked up a batch of Eastwoods Greaseess compounds and so far have mixed opinion of them. Tried the 80 grit compound and it seems flaky. I guess i should have gone with greased versions.

One thing i can say so far for sure is that buffing compound grit does not match up to other abrasive methods by grit scale. I have allot of experience sharpening knives and in knife sharpening I could go from 10K stone (1 micron abrasive particle size) to 0.5 micron grit on a strop. With buffing compounds it seems like i have to go backwards by a factor of 5. That is to start using 80 grit buffing compound on a soft wheel i'd need to finish a part with like 400 grit abrasive. So, compound grit numbers are deceptive in that sense. I think I am going to invest into 6" line of 3M bristle disks, still need 120, 220 and 400 disks. From there I can go to compounds. My initial hope was that I can use 80 grit compound on a soft wheel to remove milling marks and let wheel "flow" into contours of the part that my belt sander can't get into, but after messing around with couple versions of compounds I don't think any of them are aggressive enough to remove milling marks, or at least not when applied to soft wheel, which can "flow" into odd geometries.

UPDATE:
Tried to mess with greaseless compound bit more and I must say: Interesting Idea. The compound in the package is flaky and looks like old, crappy compound, however this is far from the truth. The compound melts at relatively low temperature and it melts onto the buffing wheel, basically turning the wheel into sand paper. I suspect that with light pressure and low heat build up during buffing itself the grit will stay affixed to the wheel and function as sand paper. Not sure yet what will happen with prolonged buffing and increased temperatures. I only tried the 80 grit compound and the wheel was slinging the compound all over the place, made a mess in my garage and DEFINITELY MADE ME APPRECIATE THE FACT THAT I WAS WEARING FULL FACE SHIELD. Still have bits and pieces of it stuck on my shirt.
 
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