finishing plasma cut pieces with a drum sander

[flyinwilly]

I recently received a very large order for a device I make. It has 5 pieces so it so that makes for a lot of finishing work. I used to do it with a flap disc but doing a 1000 pieces at a time by hand is a no go. I knock the slow speed dross off with a needle scaler and then finish the pieces on a drum sander. It is doing OK but because of the slight warping when cutting, it hits the high spots and misses some of the lows. Even with that, it has cut my finishing time by 60-70%. I had a thought that if I glued a 1/8" rubber cover on the drum to go under the sandpaper, it would flex enough to give a better finish. Has anybody tried this or have any suggestions ? Any help would be appreciated.

[weldguy]

For that many parts the only way I would go is a muriatic acid/water bath. Throw them in overnight, come back in the morning and they will look perfect. Will blow your mind how well it works and save you tons of time.

[flyinwilly]

will that remove the fine dross that I miss with the needle scaler ? What is the mix on the muriatic acid ?

[adbuch]

I recently received a very large order for a device I make. It has 5 pieces so it so that makes for a lot of finishing work. I used to do it with a flap disc but doing a 1000 pieces at a time by hand is a no go. I knock the slow speed dross off with a needle scaler and then finish the pieces on a drum sander. It is doing OK but because of the slight warping when cutting, it hits the high spots and misses some of the lows. Even with that, it has cut my finishing time by 60-70%. I had a thought that if I glued a 1/8" rubber cover on the drum to go under the sandpaper, it would flex enough to give a better finish. Has anybody tried this or have any suggestions ? Any help would be appreciated.

Is this a power fed drum sander where you feed the parts thru on a belt? Or are you doing it by hand with a drum sander? What I mean is the hand held units. Thanks,
David

[flyinwilly]

it's a power fed drum sander, Performax 16-32. As long as you don't take too much of a bite, you can feed the parts in as fast as you can get them on the belt. The drum is solid steel, not inflatable, and I think if I put a softer surface under the paper, it will do a better job. Trying to find out if anybody has tried this out.

[adbuch]

OK - now I understand. That makes sense that if there was some sort of thin "cushion" between the paper and the drum, this could allow a little bit of "give" or cushion to help you with your warped material. Perhaps you could contact the manufacturer to see if they offer something like that.

I would love to have a power fed drum sander like that, but it's just too expensive for the little bit of cutting I do. But If I were in business making many, many parts such as you are doing, I would most likely buy one like yours or the TimeSaver brand I have also seen.

Thanks,
David

[weldguy]

will that remove the fine dross that I miss with the needle scaler ? What is the mix on the muriatic acid ?

Oh ya it will remove ALL the dross, you will be amazed at how the parts look when they come out, smooth, clean, dross free, and zero effort. I use a 50-50 mix with water. Try it in a small plastic container on 1 or 2 parts to see what you think before filling up a big tub for your big job, will only cost a few bucks to try it. Curious how you find it works for you.

[SegoMan DeSigns]

Here is the Timesaver brand belt sander in action:




Link to their site:

https://timesaversinc.com/

[adbuch]

Here is the Timesaver brand belt sander in action:




Link to their site:

https://timesaversinc.com/

Nice!!

[flyinwilly]

Tried the muriatic acid bath on a few small pieces and it does remove the dross. However, after rinsing in a baking soda bath and drying, they rusted within 24 hours. I know it's just a very light surface rust but it has to be cleaned off before I can assemble, weld, and paint the units. I ran almost a thousand pieces through the drum sander, both sides, with 120 grit, alum zirconia paper in a little over three hours. Had to change the paper once and that took 20 minutes. I figure the paper cost of $10 and three hours labor is pretty cheap because I was all done with the cleaning and no rust. It takes time to knock the heavy dross off with the needle scaler but I do that while the plasma table is cutting the next batch of parts. I am still going to add the rubber pad to the sanding drum to give the paper a little more flexibility when it contacts the pieces. It's on order and I'll let you know how that works.

One problem with the drum sander is each piece MUST be larger than 6 inches. It has to remain in contact with either the infeed or outfeed rollers. If it doesn't, it will shoot out the front at you like a missile. Another thing that may not work for everyone is that the finest grit zirconia paper I can find is 120. It leaves relatively course sanding marks. This doesn't bother me as the pieces are painted with an epoxy primer and a acrylic urethane topcoat so they come out nice and smooth. Even with these two drawbacks, I'm very satisfied with the performance of the drum sander.

Willy

[SegoMan DeSigns]

Thanks for the update Willy,

That is a relatively low clean up cost.

[adbuch]

This is very good information to know. That is interesting that the parts rust so quickly, and could certainly be one of the drawbacks to using the acid bath for dross removal. I wonder if there is a different process you could use for step 3 after your baking soda bath. In the past I have used Dupont Metal Conditioner (acid formula that can either be used full strength or diluted with water) for treating bare metal auto body parts (fenders, doors, etc.) after media blasting and it keeps them from rusting. The truck in the photo below was blasted to remove old paint/primer and then treated with Dupont Metal Conditioner over 10 years ago and it will not show rust, even in humid weather or with the evap. cooler blowing on it. So this might be an option.

David

20210710_214357_resized.jpg

20210710_214416_resized.jpg

[weldguy]

Yes, after the acid the parts are as bare steel as it gets and they will show signs of rust quickly. I forgot to mention that. If I need to store the parts for any length of time before they are assembled I sometimes give them a quick mist of WD40 which the welder burns off no problem when the time comes. Also most of my stuff is powdercoated and everything is sandblasted first so again not an issue with some rust dust on it. Hey, whatever works for you, that's the important part but glad you tried it.

[flyinwilly]

Final report on drum sander finishing on plasma cut parts.Attached a 1/16 inch silicone rubber sheet to the sanding drum. Used Gorilla double sided tape to hold in place. The sanding paper will really lock it in place. Ran a few test pieces through and they came out beautifully. Much smoother than the paper directly on the drum. Only tried 4 pieces but none required a second pass. It cleaned up the edges nicely as well as the middle sections. Still have to knock off the heavy dross with needle scaler but I think I've found my permanent grinding solution. Fast, good quality, and cheap - can't beat that.

Willy

[adbuch]

Willy - that sounds great! Glad to hear the cushion under the sanding paper works so well.
David

[acourtjester]

since this is about dross removal here is a neat electromagnetic a guy setup to hold small steel parts for grind on for cleaning so here it is.

from Amazon
Electromagnetic Lock 150LBS 60KG Holding Force Electric Magnetic Door Lock 12V Fail Safe NC Mode for Access Control System
Brand: YUANWIN
$19.99

[plasmanewbie]

Clever, thanks for the vid AC