Author Topic: Tips for working with aluminum (Read 57017 times)

Cheese · « **Reply #150 on:** June 07, 2023, 02:07 PM »

Quote from: rvieceli on June 03, 2023, 12:42 PM

@Cheese did you get those hook and loop 3M scotchbrite disks? Had a chance to use them yet? Curious about how they perform. Thanks Ron

Hey Ron @rvieceli I finally received the backing pad. Before I received the 3M backing Pad for the AGC, I tried using the Scotch-Brite™ Precision Surface Conditioning Discs on the RAS 115. Initially they held fine until the RAS was removed from the surface, at that point the RPM's increased and the discs would usually jettison themselves from the sander.

I really like the Surface Conditioning Discs as they impart a nice uniform finish to the metal. They aren't nearly as aggressive as the Scotch-Brite™ Clean & Strip discs.
The Scotch-Brite™ Clean & Strip discs work well for striping paint, coatings, adhesive or mill scale and rust. They don't load-up but they do leave a very slight surface texture. It would be best to then paint the surface (powder coating would probably be ideal) or if you want a more decorative finish, further refine the surface using the Scotch-Brite™Precision Surface Conditioning Discs.

Here's a RAS Scotch-Brite™ pad with an aluminum round placed on top and a Scotch-Brite™ Precision Surface Conditioning Disc with the same aluminum round. Quite a difference in stiffness.

A sample of the 5 grits available, extra course, course, medium, fine & very fine.

Here's the 3M backing pad. It comes with 3 different sized nuts for 10 mm, 14 mm or 5/8-11 threads. The plastic piece fills in the middle of the pad if the discs have 5/8" diameter center holes.

Here's a comparison of the hook & loop between the 3M pad and the RAS pad...quite significant.

The Precision Conditioning Disc and a comparison to the Clean & Strip Disc.

rvieceli · « **Reply #151 on:** June 07, 2023, 05:33 PM »

@Cheese thanks for the info. I have tried the XT Pro disk before and just ordered another to try again. Personally I love 3M scotchbrite stuff and believe that you are just throwing money away if you buy anything other than 3M rolocs.

I’m not sure I feel the same way about the larger RA grinder disks. They cost 3-4times more than the imports I have been using but don’t last 3-4 times longer. The do last longer and do a great job but a perhaps too high a premium.

I’ll give them another shot with this new order. I really need something for heavy duty removal and thr precision disks may be too refined for my process.

Ron

Cheese · « **Reply #152 on:** June 19, 2023, 02:15 PM »

I recently ran across these two 3M White Papers on Cubitron™ II materials. Pretty interesting read...

It all started as I wanted to purchase some new 6" x 48" belts and I noticed that 3M pricing ranged from $14 to $44 for the same size Cubitron belt...Why?

https://multimedia.3m.com/mws/media/1310315O/effects-of-pressure-on-performance-of-abrasive-belts-white-paper.pdf

One paper gets into the differences between crushed ceramic grain materials and Precision Shaped Grain (PSG) ceramic materials and the differences in abrasive life and the amount of heat that's put into the substrate.
I do know that when using the Scotch-Brite™ Precision Surface Conditioning Discs with a PSG coating, the stainless doesn't get nearly as hot as it normally would. I'd typically work an area of the SST item and then move on to an entirely different area to allow the first area to cool down before returning to the first area to complete the job. The difference is quite noticeable.

https://multimedia.3m.com/mws/media/1381348O/advancements-in-abrasive-grain-white-paper.pdf

The other paper gives a history of abrasives that goes back to the use of shark skin as an abrasive material. It also gets into the difference in shapes between crushed ceramics & PSG ceramics.

squall_line · « **Reply #153 on:** June 20, 2023, 12:16 PM »

Quote from: Cheese on June 19, 2023, 02:15 PM

I recently ran across these two 3M White Papers on Cubitron™ II materials. Pretty interesting read...

This is amazing information!

It also goes a long way towards disproving the whole "it's just marketing gibberish" theory that competitors or others may try to throw around when attempting to discredit 3M products.

Michael Kellough · « **Reply #154 on:** June 20, 2023, 02:35 PM »

I was using the Festool edge sanding rig this morning. Festool Rubin was slow so I tried some Cubitron II. This stuff.

I thoroughly mark the surfaces to be sanded with a very soft graphite pencil so I know when sanding is finished and in this case when the angle of the edge sanding rig is off.

I was using 120 grit Rubin so went with 180 Cubitron knowing it is more aggressive and leaves a courser surface that al ox abrasives. It took only one pass to eliminate the pencil marks. I changed to 220 grit Cubitron and it also only needed one pass, and the surface is still courser than what the 120 grit Rubin was leaving.

Cheese · « **Reply #155 on:** June 20, 2023, 03:28 PM »

So, trying to understand the price difference in 3M Cubitron abrasive belts was an interesting and very educational process. A rabbit hole worth falling into.

From one of the 3M White Papers,

"UNDERSTANDING BELT AND APPLICATION PRESSURE"

"Combining the right belt with the right application pressure is essential to reaching the optimal breakdown point of an abrasive. The wrong variable in either of these fields can lead to suboptimal results evident on the workpiece and the used belt. Using either excessive pressure or insufficient pressure during grinding can have effects on the performance of an abrasive and the materials it’s grinding."

3M varies the "bond strength" (my nomenclature, not 3M's, they just refer to belt numbers) for use with the various grinding pressures that can be attained. So a 947A belt is for low to medium pressure, 784F for medium pressure and 984F for high pressure. All the belts are coated with Cubitron™ II ceramic particles but the price point for the same sized belt goes from $14 to $24 to $44. The higher the intended pressure the higher the belt price. Non-Cubitron belts for woodworking only, which use Aluminum Oxide particles, are in the $9-$10 range.

But here's the kicker, the 6" x 48" belt used on common stationary sanders like this

cannot, by it's design, generate a high enough pressure to breakdown the abrasive particles. 3M refers to this type of sander as "Slack of Belt Sander". Without the proper amount of pressure, the belt will glaze over and the belt life will be short lived. This is a great example of not needing to spend $44 for the most expensive...highest tech belt that 3M makes. A $14 belt for low pressure use on this style machine is actually a better choice and will give a longer life than the more expensive ones.

None of the issues I'm talking about really apply when sanding/grinding wood substrates, for that any GOOD belt will do, but these are issues when grinding metals, stone, ceramics or glass.

Here's a material chart and a belt selection chart. They go hand-in-hand with this brochure in identifying the various belts needed for various pieces of equipment.

https://multimedia.3m.com/mws/media/926870O/3m-industrial-products-for-metalworking-catalog-hi-res-pdf.pdf

Mini Me · « **Reply #156 on:** June 20, 2023, 09:52 PM »

I note the belt speed specification in one of the tables and wonder how many variable speed linishers are sold to the hobbyist sector of the market. I made my own machine which has speed control but I doubt many others have speed control and like myself even know of its importance. A rabbit hole indeed and thanks for your efforts in the rabbit hole.

Richard/RMW · « **Reply #157 on:** June 24, 2023, 05:55 PM »

@Cheese you sidetracked my usual habit of scanning mostly through a post then dashing off a half-baked comment and moving on. I actually had to read the info you referenced and I'm still not certain I understand which belt to use for AL. I did get far enough into the maze to figure out that 3M doesn't make 12" Cubitron disks, which brought me to a temporary halt. I need to delve back through it again. Thanks for providing the context.

I'm down to my last couple of disks and the one on the machine is ready to be replaced. They use a particularly nasty PSA that necessitates scraping off the disk surface and scrubbing it with lacquer thinner, it's enough of a PITA that I'll run a disk well beyond the point it should be replaced.

RMW

Cheese · « **Reply #158 on:** June 24, 2023, 11:57 PM »

Quote from: Richard/RMW on June 24, 2023, 05:55 PM

I'm down to my last couple of disks and the one on the machine is ready to be replaced. They use a particularly nasty PSA that necessitates scraping off the disk surface and scrubbing it with lacquer thinner, it's enough of a PITA that I'll run a disk well beyond the point it should be replaced.

I hear you, I've had just the opposite problem, The previously purchased non 3M 12" sanding discs were initially slightly cupped and thus, after some time, prematurely released themselves from the platen sanding surface. This meant that every time I used the sander, I would have to push the cupped sanding disc to the platten or risk that the sanding disc would destroy itself once it was turned on. What a nuisance.

Actually 3M does offer large discs up to 36" in diameter which makes sense as Baldor, Baileigh & Kalamazoo offer large disc stationary
grinders. I've recently ordered and received 12" sanding discs and will get back to you with the grits and the part numbers. It's confusing as the number of sanding products that 3M offers is incredible and difficult if not impossible to track. Add in the the fact that you want to purchase a single item rather than a box of 12 each and the purchasing task is daunting.

Richard/RMW · « **Reply #159 on:** June 25, 2023, 06:11 AM »

Needed to lop off the heads of some old dogs (they refused to learn new tricks...) and the grinder jig came in handy again. The beheading:

The 20mm section was 18mm under the head, after the bandsaw cut the target was 16mm finished length. The little angle is 1.5", so the setup used a 1.5" gage block + 16mm gage block: (It's the last rodeo for this disk)

I'm still a little surprised at how easy & accurate this jig is, the results were bang on 16mm fresh off the sander, ready for lapping on the surface plate.

Finished dogs with a M8 countersink.

Lots more aluminum chips were flying around the shop yesterday, but that's another story. I did take the plunge and replace the disk; I wish I could figure out where I got these as they have lasted really well.

RMW

EDIT: after a little sleuthing I did manage to find the same sanding disks.

Now all I have to do is justify another $45 in abrasives I "need" to reach the free shipping level, and I'll have a lifetime supply of disks/addition to the estate sale inventory. Or find a similar USA made zirconia disk and see if they hold up as well. I'm inclined to go with the proven alternative.

@rvieceli another "buying supplies" quandary.

RMW

Crazyraceguy · « **Reply #160 on:** June 25, 2023, 08:08 AM »

Quote from: Richard/RMW on June 24, 2023, 05:55 PM

I'm down to my last couple of disks and the one on the machine is ready to be replaced. They use a particularly nasty PSA that necessitates scraping off the disk surface and scrubbing it with lacquer thinner, it's enough of a PITA that I'll run a disk well beyond the point it should be replaced.

RMW

There's a little body shop trick that I learned back in the early 90's to mitigate that problem.
Of course, you have to go through the PITA to get the platen clean first, but hopefully it will be the last time.
You simply stick the new abrasive disc to your shirt, pull it off, and re-stick it (in a different place) then apply it to your machine's platen. The fibers and dust from your shirt will interfere with the "over-bonding" that most PSA discs experience. It won't make it so bad that it won't stick properly, but it will come off much easier the next time. If your shirt is sweaty, stick the disc to a cotton rag, stretched out on the bench top. Sweat is too much.
I do this with the 8" geared orbital sanders that I use for leveling solid surface seems. Ingersol-Rand 328b. The bigger problem with them is that the platen is not metal, therefore harder to clean. It's an aluminum backer with a dense foam padding and some kind of plastic skin? PVC maybe? so cleaning it with solvent takes a lot of care, which is why I avoid it like the plague. The shirt fibers do the trick.

@Cheese do you have a part number for that 3M disc that fits the RAS?

Cheese · « **Reply #161 on:** June 25, 2023, 10:30 AM »

Here's the disc that I mentioned that was cupped, it adheres initially but after 4-5 minutes it starts to release from the platen. You can see that it's not really been used a lot.

So I finally purchased a couple of Cubitron discs in 60 & 80 grit. I may also purchase one in 120 grit...we'll see how these work.

This next part is for you @Richard/RMW ...for 12" discs 3M strangely produces a limited assortment. For general woodworking they produce the 348D series which uses aluminum oxide grit. The other series is 777F which uses an aluminum oxide & ceramic matrix, and is known as Cubitron. Cubitron II is also aluminum oxide & ceramic however it is a Precision Shaped Grain (PSG) product and oddly not available in large 12" diameter discs.

Cubitron & Cubitron II can both be used on stainless and produce a reduced level of heat when used on SST. Cubitron produces less heat through a coating while Cubitron II produces less heat because of the PSG grains. Here's an example of Cubitron vs Cubitron II products.

And finally here are the 3M 12" disc numbers for both 348D & 777F. Also here's the vendor I purchased them through because they are offered in single quantities.

https://www.rshughes.com/p/3M-348D-88903-PSA-Disc-12-In-60-Medium-Aluminum-Oxide/051144_88903/

https://www.rshughes.com/p/3M-Cubitron-777F-88871-PSA-Disc-12-In-60-Medium-Ceramic/051144_88871/

Cheese · « **Reply #162 on:** June 25, 2023, 11:22 AM »

Quote from: Crazyraceguy on June 25, 2023, 08:08 AM

@Cheese do you have a part number for that 3M disc that fits the RAS?

Just so that you're aware @Crazyraceguy there is a considerable difference between the hook & loop profile of the RAS pad versus the 3M pad. Which means that the Scotch-Brite disc can be attached to the RAS but it's not a solid connection. You have to be careful because the Scotch-Brite disc can jettison itself at maximum RAS speed. Here's a comparison between the RAS pad & the 3M pad and the part numbers of the Scotch-Brite discs I purchased.

rvieceli · « **Reply #163 on:** June 25, 2023, 12:00 PM »

A sometimes good source for 3M abrasives locally is an auto parts store that caters to body shops. They don’t usually have everything and usually not 12 inch disks. But my local one will sell one sheet or one roloc if you want try something or open a box you thought was half full to find it empty.

Ron

Crazyraceguy · « **Reply #164 on:** June 25, 2023, 05:51 PM »

Thanks @Cheese that's what I was looking for. Seems like the 88656 backing pad is the one I need.
Festool's hook and loop is quite different from the rest of the brands, so compatibility issues might be solved by this. The main thing is that it can get me into 5" paper, in which I have far more variety of grits, plus the Scotch-Brite.

Cheese · « **Reply #165 on:** June 25, 2023, 06:56 PM »

No @Crazyraceguy you don’t want that pad, it’s a hard backer pad for Cubitron grinding discs. Let me get back to you later tonight after I’m done preparing dinner. Chicken tacos with tomatillo/poblano sauce.

Richard/RMW · « **Reply #166 on:** June 25, 2023, 08:05 PM »

@Cheese thanks for the info and links. I couldn't find those disks when I search thru the 3M PDF catalog.

RMW

Cheese · « **Reply #167 on:** June 26, 2023, 12:00 AM »

Quote from: Cheese on June 25, 2023, 06:56 PM

No @Crazyraceguy you don’t want that pad, it’s a hard backer pad for Cubitron grinding discs. Let me get back to you later tonight after I’m done preparing dinner. Chicken tacos with tomatillo/poblano sauce.

If I remember correctly, the RAS has a M14 thread, so that's fact number one.

Secondly the RAS is 115 mm while the 3M discs are 125 mm so that's fact number two.

The 3M pad needed for the Scotch-Brite Precision Surface Conditioniong Discs is 3M p/n 89871 which is 125 mm in diameter and comes with nuts that will fit M10, M14 & 5/8-11 threads. It looks like this.

The 88656 pad you referred to looks like this. It's a back-up pad used on Cubitron fiber discs.

I guess you have some options but you need to decide which options are amenable to you.

Unfortunately the 3M pad will not fit within the RAS without removing the RAS guard/vacuum housing surround or modifying the pad and the 3M discs.
I'd start with ordering a couple of 3M Scotch-Brite discs, attaching them to the current RAS pad and see if that meets your needs. And then go from. there.

Cheese · « **Reply #168 on:** June 26, 2023, 12:05 AM »

Quote from: Richard/RMW on June 25, 2023, 08:05 PM

@Cheese thanks for the info and links. I couldn't find those disks when I search thru the 3M PDF catalog.

RMW

So you're good to go? Mother mining can be very confusing at times.

Cheese · « **Reply #169 on:** June 26, 2023, 12:47 AM »

@Crazyraceguy here's some supporting evidence, the 125 mm 3M pad placed on the RAS 115. The pad overhangs the guard and yet it is still not centered as can be seen when looking at the alignment of the center of the pad and the RAS attachment spindle.

Richard/RMW · « **Reply #170 on:** June 26, 2023, 04:45 AM »

Quote from: Cheese on June 26, 2023, 12:05 AM

Quote from: Richard/RMW on June 25, 2023, 08:05 PM
@Cheese thanks for the info and links. I couldn't find those disks when I search thru the 3M PDF catalog.

RMW

So you're good to go? Mother mining can be very confusing at times.

Yep, appreciate your guidance. I'll add the Cubitron to a future order and see if it's 3X as good as the zirconia disks. It'll be interesting to see if the heat reduction applies to AL and mild steel.

RMW

Crazyraceguy · « **Reply #171 on:** June 26, 2023, 08:59 AM »

Quote from: Cheese on June 26, 2023, 12:47 AM

@Crazyraceguy here's some supporting evidence, the 125 mm 3M pad placed on the RAS 115. The pad overhangs the guard and yet it is still not centered as can be seen when looking at the alignment of the center of the pad and the RAS attachment spindle.

(Attachment Link)

Thanks so much @Cheese I had it wrong. What I was looking for was a backing pad with regular (Velcro style) hooks that fits 5" discs.

From the pics, It looks like that pad is too "flat", not enough off-set to work with the RAS? Maybe I could make a spindle adapter of sorts? An M14 internal thread and use the more common 5/8-11 outside. I'll have to measure the depth of the RAS pad to figure out the overall length.

What would be ideal is an arbor thing that would allow flap discs.

Cheese · « **Reply #172 on:** June 26, 2023, 10:28 AM »

Quote from: Crazyraceguy on June 26, 2023, 08:59 AM

From the pics, It looks like that pad is too "flat", not enough off-set to work with the RAS? Maybe I could make a spindle adapter of sorts? An M14 internal thread and use the more common 5/8-11 outside. I'll have to measure the depth of the RAS pad to figure out the overall length.

What would be ideal is an arbor thing that would allow flap discs.

The M14 internal x 5/8-11 external is a pretty common adapter, used on wet tools so there's usually a small coolant hole through the center.

I'll take a couple of side view photos showing the 3M pad placed on the RAS. I'm assuming you want to retain the stock RAS dust collection guard & brushes?

Cheese · « **Reply #173 on:** June 26, 2023, 12:39 PM »

Hey @Crazyraceguy here are some interesting photos for the RAS.

I don't know if you're aware of it but Festool does offer a pad that you can attach 4-1/2 sanding/grinding discs to, 485298.

Here's a side view of the RAS pad on the left & the 3M pad on the right. There is an 18 mm height difference between them so an adapter may work, it just needs to be the correct length.

Crazyraceguy · « **Reply #174 on:** June 26, 2023, 04:57 PM »

@Cheese that's great information. Thank you so much.

Cheese · « **Reply #175 on:** June 28, 2023, 11:27 AM »

Quote from: Crazyraceguy on June 26, 2023, 08:59 AM

Thanks so much @Cheese I had it wrong. What I was looking for was a backing pad with regular (Velcro style) hooks that fits 5" discs.

From the pics, It looks like that pad is too "flat", not enough off-set to work with the RAS? Maybe I could make a spindle adapter of sorts? An M14 internal thread and use the more common 5/8-11 outside. I'll have to measure the depth of the RAS pad to figure out the overall length.

What would be ideal is an arbor thing that would allow flap discs.

If you remove the RAS housing, the 3M pad will easily fit on the RAS and for surface conditioning as compared to surface cleaning, that's not a bad option as the material removal will be insignificant.

Take the 3M pad & remove the 5/8-11 nut and install the M14 (black) nut. Attach the 3M pad and you're done.

Richard/RMW · « **Reply #176 on:** June 28, 2023, 01:36 PM »

@Cheese is it an optical illusion or do the threads extend above the pad?

RMW

rvieceli · « **Reply #177 on:** June 30, 2023, 12:22 PM »

On the subject of disk sanders, Ameribrade seems to be coming out with a very nice looking albeit expensive piece of kit. Seems well thought out and fitted out for different operations

Here’s a link to the presale page:

https://www.ameribrade.com/hyper-disc-bench-grinder

Ron

Cheese · « **Reply #178 on:** June 30, 2023, 12:50 PM »

Quote from: Richard/RMW on June 28, 2023, 01:36 PM

@Cheese is it an optical illusion or do the threads extend above the pad?

(Attachment Link)

RMW

Ya @Richard/RMW the threads do extend above the pad but placing a thick washer between the pad & the arbor would take care of that issue.

Cheese · « **Reply #179 on:** July 01, 2023, 11:28 AM »

I recently received the 3M belts I ordered, an aluminum oxide 36 grit, and a 60 grit & 120 grit Cubitron II. The 36 grit will be for wood use only (probably) while the other 2 will be used on both wood & metals. Here are a few photos of the belts for quick identification purposes.

Aluminum oxide on the top, Cubitron II on the bottom.

Here are the important belt identifiers:
Red = grit
White = grit material
Blue = grit bond strength