A very inexpensive tumbler

[panozeng]

I recently got my homebuilt cnc plasma going, and am looking for ways to clean up the parts that I cut on it. By my thinking I really need 2 different machines and processes. I figure I first need a very high energy shaker type machine that would quickly knock the dross off the parts. I'm thinking something along the lines of a paint chaker to really get the parts moving fast. Then I'd switch them to a conventional vibratory machine to deburr the edges, remove mill scale, and put a uniform finish on everthing.

So, as a starter I made a quick and dirty rotary tumbler that I could run in my lathe. It's based on a 5 gallon "Homer Paint Bucket" from Home Depot ($2.49). I added 2 ribs on the inside to help make the material move. I also made a plate that fits tighly in the bottom of the bucket and bolts to it with a 1.25" tube welded to the center to chuck on in the lathe. Another plate with a center hole reinforces the lid and lets a center in the tailstock provide support.

I loaded the bucket with plasma cut parts, some #57 gravel, and some water. The nice thing about my lathe is it is variable speed - so I was able to gradually increase the speed while listening to the action inside. I found 2 different speeds that I think were important. First, a slower speed that resulting in the most continuos "grinding" noise inside and second a faster speed that resulted in 2 hard crashes per revolution. I figured the slower one does more surface work, and the faster one was higher impact energy to knock dross off.

Anyway, it works but is not as good at getting the dross off as I'd hoped. I think it requires a little more energy to accomplish that. Here is a video of it running at the slower speed:

[nomedia="http://www.youtube.com/watch?v=Z7FURzJPJcc"]YouTube - Plasma Cutter Running Mach3[/nomedia]


And here are some before and after pics of the same parts:

[levelzero]

Nice strut brace

I do mostly aluminium but from my experience you'll need a heavier media (off cuts work well) and a fair bit of time. I tumble my aluminium parts for 3-5 hours to debur and knock the edges down.

[DareBee]

Nice parts.
Love the cars you guys build.

You want to make some time deburring you will need a wheelabrator TumBlast.

[panozeng]

Actually I have not worked there since 2008; although I still do a lot of tube work for them. In fact, I'm working on stuff for them right now, and built the cages that are in the new Abruzzi race and street cars.

I just bought a used automotive machine shop tumbler that is intended for doing valves, etc, that seems to work well. It is enclosed and splashes through water and detergent as it rotates. The gearmotor says 40 rpms. It came with steel media; 5/16" dia cylinders with angled ends that work pretty well. But, I found that since this media is not abrasive it tends to leave a little flash on the edges - it peens it out flat, but doesn't remove it. I then tried it with inexpensive lava rock from home depot instead of the steel shot and it did a great job in 20 minutes! Best part is this machine is pretty quiet!

I am still going to build a vibratory machine, as I think they have the most potential. Thinking a 55 gallon plastic drum on its side like others have done recently.

Oh, and yes, that is a strut tower brace. Goes on a 2nd gen RX-7 with Chevy V8 conversion...

[Switcher]

You might want to read this forum post for a diy tumbler.

I think you could use a 55 gallon steel drum instead of a cylinder tank.

Another DIY Tumbler

[levelzero]

Oh, and yes, that is a strut tower brace. Goes on a 2nd gen RX-7 with Chevy V8 conversion...

Nice, I actually have a pair of second gens. I recently made a rear strut brace/harness bar for one and a front strut brace is an upcoming project for the other.

[jimcolt]

Actually, it is much easier if you just cut the parts dross free. I cut everything up through 3/8" with my plasma cutter with no dross, with the occasional exception of a bead on corners that pretty much falls off with handling. The key to dross free cutting?
1. A good quality plasma system with the latest torch technology.
2. Matching the right consumables and power level to the materials you are cutting.
3. A good torch height control that always pierces at the correct height (keeps the torch nozzle (tip) in good shape, then cuts at the right height (controls dross and angularity) within .010" of the torch manufacturers recommended height.
4. Good cnc machine motion with maximum accleration (plasma likes good acceleration in and out of corners and fine features, sluggish acceleration makes dross)

Jim

[panozeng]

Hey - we don't all have unlimited access to the complete line of Hypertherm products like you... However, while it's outdated technology I have at least purchased a Hypertherm machine to use rather than the Esab...

[jimcolt]

Ha ha!. I'm not sure why you think I have access to the complete line of Hypertherm products like I do. I use a Powermax45 (45 amp air plasma) on my PlasmaCam machine in my home shop. I was just describing the parameters that are important wth plasma cutting that can eliminate secondary operations (such as dross removal). I would love to have a tumbler in my home shop as well, but I wouldn't want to use it for dross removal if I could easily dial in the cutting process to eliminate dross. Saves a lot of time and hassle!

If I had access to Hypertherms line of products I would have used a high definition system to cut 1/4" plate with square, clean edges and no dross! Unfortunately, even though I work for Hypertherm, I have to buy the equipment for my home shop, and I have to buy the consumables as well.

Jim Colt