[Iron-Man]

Its taken a long time, but here are some pictures of what I have been working on. It all started out with the dsPIC servo, http://www.cnczone.com/forums/open_s...c-servo-6.html. See all my posts. I am just about finished with the entire design. Still some tweaking, powder coating, etc. left to do. The one issue that I have now is, the OPA 549s require a split power supply. The tab on the OPA 549 is connected internally to (V-). As of now, the OPA 549s are not connected to their respective Al heat sinks. What I thought was a design flaw in the original circuit boards is a blessing. I measured a voltage of 24 V when I connected a probe between the tab and the power supplies cases which are connected to the Al panel. I believe that it is a result of the two supplies being connected, (V- |V+) for the common output. The supplies are 24V each @ 12.5 amps. I will need to use some kind of thermal adhesive or pad to provide a electrically non conductive but thermally conductive path to the Al heat sinks. The servo reducer assembly was my first powder coated part. Sorry about the bad pictures, will clean up when almost complete. By the way, what is the optimum video resolution and video recorder to use for youtube?

Let me know what you-all think.

Iron-Man

[bogus105]

nice job Iron-Man!
you mean that red coating when talking about first powder coated part? how you doing it? that red aluminium part looks like after electrical oxidation of aluminium. Do you perform that coating in home conditions?
As regards YT video resolution - the bigger the better

[Iron-Man]

nice job Iron-Man!
you mean that red coating when talking about first powder coated part? how you doing it? that red aluminium part looks like after electrical oxidation of aluminium. Do you perform that coating in home conditions?
As regards YT video resolution - the bigger the better

Yes, I did the coating in home conditions. I studied all the information that I could find on powder coating, pros vs cons what to do, what not to do, etc. I used a system from: Chicago Electric Coating System I used an old toaster oven to cure the part. It was a bit of trouble getting it into the oven without touching the sides, but I am happy with how the part came out. Thanks for the comments.


Iron-Man

[Iron-Man]

High Resolution Image.

Specs:

Servo Motors Litton-Clifton precision.
Belt reduction 3:1 ratio.
Torque 49.5 oz-in continuous / 375-oz-in peak.
Encoder 500 cpr x 4.


Iron-Man

[Fastest1]

That red stepper gear cover is anodized isnt it? It looks too deep for powder coating. Looks great either way. Great to see you on the porch too!

[Riceburner98]

If there's a version of anodizing that involves coating a part with red powder, then baking it in a toaster oven, then yes, it's anodized. LOL

Most people would call that powder coating though. Tough to fit the acid baths needed for anodizing into a toaster oven...

He did a great job with the powder, it looks great!

[SCzEngrgGroup]

For anyone wanting to get into DIY powder coating, this gun is hard to beat:

NEW Craftsman Powder Coat System SYSTEMS ITEM # 17288 - eBay (item 110573585007 end time Nov-12-10 11:31:44 PST)

I have an air-powered one like the OP used, and one of the above Craftsman electric ones. I'd take the electric one over the air-powered one any day. It's quicker, easier, less fussy, and delivers a much more reliable flow of powder. I've done hundreds of parts, and it works amazingly well. Just get yourself a scrap electric oven to bake the parts, and you're in business. Do not do it in your kitchen over, or you may need a divorce lawyer.... The over I used for years came out of someones trash, and has only a single working heating element, but does the job perfectly. I bought another, nicer one, with digital control, off Craisglist for just $50 last year. Just be sure to check the thermostat calibration - most older ovens are pretty bad. A convection oven would be perfect, as it will provide more even temperature throughout the entire space.

Regards,
Ray L.

[Riceburner98]

I've got a convection countertop "mini oven" that I'm dying to use... It's the size of a large toaster oven. I've got an air-powered gun as well, but it's 70 miles away at a friend's house. I used it once, then left it + the powder in my car. Unfortunately it was summer, and the powder baked itself into big lumps in the heat. I should get the Craftsman one and set up the oven outside.

Iron-man - what powder did you use? Just a standard red, or something that was designed to look "anodized" like that?

[Iron-Man]

I've got a convection countertop "mini oven" that I'm dying to use... It's the size of a large toaster oven. I've got an air-powered gun as well, but it's 70 miles away at a friend's house. I used it once, then left it + the powder in my car. Unfortunately it was summer, and the powder baked itself into big lumps in the heat. I should get the Craftsman one and set up the oven outside.

Iron-man - what powder did you use? Just a standard red, or something that was designed to look "anodized" like that?

Candy Red Translucent; Candy Red Translucent TGIC . To get the desired effect on Al, it has to be polished to a mirror finish. I did this with 600 grit sand paper and then used buffing compound to get the mirror finish. You can also powder coat with a chrome finish and then follow up with the translucent candy red. Although, I am not sure if my single voltage gun can do this.

Iron-Man

[Fastest1]

I didnt know they had translucent powder coating. It looks great. It must be a clear since the metal has to be polished. Regarding your polishing, you went to a buffing wheel right after 600 grit? I have polished plenty of aluminum and I always worked to progressively finer grits starting at around 600 to oooo steel wool then the rouges. From 600 to a buffer would just polish the scratches.

[Iron-Man]

I didnt know they had translucent powder coating. It looks great. It must be a clear since the metal has to be polished. Regarding your polishing, you went to a buffing wheel right after 600 grit? I have polished plenty of aluminum and I always worked to progressively finer grits starting at around 600 to oooo steel wool then the rouges. From 600 to a buffer would just polish the scratches.

Yes, I did go to a buffing wheel from the 600 grit sand paper. I purchased this system from Sears Sears: Online department store featuring appliances, tools, fitness equipment and more ,Sears Item# 00928650000 | Model# 28650 . I used the black rouge first and ended with the red. I am sure that there are many ways to do this, but it worked ok. I am open to any suggestions for a better finish.

Thanks for the comment.

Iron-Man

[Iron-Man]

If there's a version of anodizing that involves coating a part with red powder, then baking it in a toaster oven, then yes, it's anodized. LOL

Most people would call that powder coating though. Tough to fit the acid baths needed for anodizing into a toaster oven...

He did a great job with the powder, it looks great!

Thanks for the comment.

Iron-Man

[Fastest1]

Iron man the work looked great from the pics. What I was told years ago was that the buffing will polish the highs and lows of the scratch. So you must minimize the scratches first by using successively smaller grits til the rouges. There will be a difference in sheen done this way but it is labor intensive. Great work.

[DICKEYBIRD]

Great stuff there I/M! Servos, sigh, one of these days.

Looks like your Chicago Electric powder coating machine is a bit cheaper from Harbor Freight. 10-30 PSI Powder Coating System ($59.95)

It doesn't come bundled with the supplies like your kit but I'll bet they aren't almost $100.00 worth.

I've never tried powder coating but after seeing your results, I'll have to give it a shot.

[Iron-Man]

I finally located a product to solve my heat sink problem. Just received samples today. Here is a link;
Gap Pad 5000S35 Features ~ Thermal Materials, Thermal Solutions ~ The Bergquist Company


Iron-Man

[Riceburner98]

We use those gap pads on a lot of the products where I work.. Lots of hot electronics stuffed into little camera enclosures. According to the designers they work great. I'm not totally convinced, but they're smarter than me, right? I've stuck one on my finger and pointed the heat gun at it for a while, and my finger didn't burn. You'd think it would transfer heat better than that. In some of our applications we have a stack of those things almost 1/4" thick. I guess they're better than not having any connection between the chips and the enclosure, in the case of our cameras!

In a related note, I've used a much thinner version to heat sink a TO-220 package with "live" mounting tab to a heatsink that was going to be exposed to the user. I used an insulating "post" around the screw, but you can use nylon screws + nuts as well if the heatsink isn't going to get super hot. ( I used Digikey P/N BER176-ND for a TO-220, but they have other sizes on the catalog pages nearby ) The "gap pads" are typically squishy material and can squeeze out (and then short the part to the 'sink) if you're screwing something tight to a heat sink - they're typically for when a chip is pressing against an enclosure from inside. Whereas the thin type can be torqued pretty tight without shorting...

Just a few observations, if they help any.

[Iron-Man]

We use those gap pads on a lot of the products where I work.. Lots of hot electronics stuffed into little camera enclosures. According to the designers they work great. I'm not totally convinced, but they're smarter than me, right? I've stuck one on my finger and pointed the heat gun at it for a while, and my finger didn't burn. You'd think it would transfer heat better than that. In some of our applications we have a stack of those things almost 1/4" thick. I guess they're better than not having any connection between the chips and the enclosure, in the case of our cameras!

In a related note, I've used a much thinner version to heat sink a TO-220 package with "live" mounting tab to a heatsink that was going to be exposed to the user. I used an insulating "post" around the screw, but you can use nylon screws + nuts as well if the heatsink isn't going to get super hot. ( I used Digikey P/N BER176-ND for a TO-220, but they have other sizes on the catalog pages nearby ) The "gap pads" are typically squishy material and can squeeze out (and then short the part to the 'sink) if you're screwing something tight to a heat sink - they're typically for when a chip is pressing against an enclosure from inside. Whereas the thin type can be torqued pretty tight without shorting...

Just a few observations, if they help any.

I thought about something similar. I will have to monitor the temperature and see just how hot it gets. If I have to, I will isolate the power supplies and mount the heat sink with a Al or Cu spacer. By the way, do you have any experience using ceramic bolts? That spacer, BER176-ND + ceramic bolt + Al/Cu spacer just might work better. I do not think a nylon bolt would hold up under the heat.

Thanks for the information.

Iron-Man

[Riceburner98]

Ceramic bolts? That sounds awesome! I've seen a ceramic "standoff" before being used with a 1/4-20 bolt (for high-voltage insulation probably) a guy at work was using them for something else.. Unfortunately in his application the spacers cracked from vibration. I would think as long as there's no "shock" load / extreme vibration they could work.. Do they make them in small sizes?

[Iron-Man]

Ceramic bolts? That sounds awesome! I've seen a ceramic "standoff" before being used with a 1/4-20 bolt (for high-voltage insulation probably) a guy at work was using them for something else.. Unfortunately in his application the spacers cracked from vibration. I would think as long as there's no "shock" load / extreme vibration they could work.. Do they make them in small sizes?

I have just started to research, ceramic fasteners, Ceramco, Inc. | Alumina Machine Screws, Alumina Nuts, Alumina Bolts, Alumina Washers and Advanced Technical Ceramics - Ceramic Tubes & Products - Ortech Ceramics .
I will contact each next week. Hopefully they are not too expensive.

Iron-Man

[SCzEngrgGroup]

Talking about things like ceramic bolts for something as low-tech as this is a bit over the top. Use nylon spacers around the bolts. This is how virtually all consumer electronics deal with this very common problem. They spacers are readily available, even from most electronics and hardware stores, and dirt cheap.

Regards,
Ray L.