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Old 01-17-08, 11:13 AM   #1
unkchunk
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Powdercoating-What exactly should be masked?

Sorry, I've given up searching here and other forums. Powdercoat/powder coat has been a frequent topic, but not what needs to be masked. I've gleaned a few items, but maybe comprehensive list would be better for reference. I'm going to have an old steel frame repainted (single color) and am in the process of stripping of the old paint now.

Background: 80's US made Raleigh, lugged steel road frame, forged drop outs, and threaded stem. Will convert it to a fixed gear.

----

Head tube and bottom bracket: Protect just the threading and/or the facing? Or is it better to re-tap and re-face? (I doubt this last part, but I don't know)

Seat tube: I've read that it's got to be masked or good luck getting your seat post in, but what about the little slit by the clamping part?

Small braze-ons and mounting brackets for water bottle, fender, rack, and front wheel lock: I have no idea, but I do have a tap for these.

Break bosses: Not applicable in my case, but maybe some one down the road might want to know.

Fork tube thread: I guess it has to be masked cause there was no paint on that part to start with.

Shifter bosses on down tube: I've get two square projections that the shifters connected to. I plan to use it as a fixie, but should that be masked to give me options later on?

----

Whether I'll do the masking or the powdercoaters will, I don't know yet. But in either case, I want to make sure what needs to get masked gets masked. Any other thoughts will be appreciated.
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Old 01-17-08, 03:39 PM   #2
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I don't think you need to mask anything if you have all the threads chased, BB and headtube faced and seat tube reamed, which is what you should do after any re-paint. The powdercoater is not going to paint the threads, although there will be some overspray, which will easily get cleaned up with the frame prep after powdercoating.

Also suggest bead blasting to avoid rust.
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Old 01-18-08, 11:47 AM   #3
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I don't think you need to mask anything if you have all the threads chased, BB and headtube faced and seat tube reamed, which is what you should do after any re-paint. The powdercoater is not going to paint the threads, although there will be some overspray, which will easily get cleaned up with the frame prep after powdercoating.
its also a good idea to grind the powdercoating off your clamping surfaces on the dropouts. front and rear. for a fixed gear, especially the rear because you want those track nuts to bear down on steel not powdercoat. both sides, and on the inside surface where the axle sits. On the front, both sides and the inner surface so your fork stays true. powdercoating will "round-off" at sharp edges, so if there is a build up in the drops, your axles won't sit correct.

Also suggest bead blasting to avoid rust.[/QUOTE]
+1
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Old 01-18-08, 07:03 PM   #4
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Thanks for the replies. I just wanted to make sure what needs to get done, gets done before. It goes in Monday and I should get it back in about a week. I opted for the bead blasting, seems to be universally recommended.

Apart from using Frame Saver, I didn't think much about the post painting work.
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Old 01-18-08, 07:13 PM   #5
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Powdercoating is not easy to remove. If the person doing the coating sprays anything into threads, faces or dropouts, you will have one hell of a difficult time removing it.

Make sure they know what to plug/mask before it gets powdercoated.
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Old 01-18-08, 07:44 PM   #6
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!!! Mask the whole steerer tube and crown race/where the crown race sits.
I did not and the tool to re-face where tht crown race fits would not fit around the steerer tube (powder coats are thicker than paint - about 0.1mm or so) and I was forced to remove the powder coat by grinding with a dremel tool in order to press the crown race back on.
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Old 01-18-08, 07:50 PM   #7
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Powdercoating is not easy to remove. If the person doing the coating sprays anything into threads, faces or dropouts, you will have one hell of a difficult time removing it.
wrong.
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Old 01-18-08, 08:07 PM   #8
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wrong.
Yes, you are.

Any other insightful comments?
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Old 01-18-08, 08:31 PM   #9
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re:

I powder coat frames for friends and such....

You need to purchase some special tape used for masking powder coating. It is typically greenish in color. It is heat resistant and will withstand the temp. of the bake oven. All other tapes will melt in the oven.

Mask all braze-on's. Mask the inner 3/4" inch of the head tube openings and seat post. Buy the needed screws and insert them into any exposed threads that you need. Any exposed threaded opening will be coated with powder and the only way they will be usable again is to have them tapped.

A typical powder coating will vary from 1.5-3 mil's. Be sure to mask the race on the fork. Mask off the opening to the BB. I have an extra set of cups that I screw into the BB to cover them because it is difficult to mask that area.

I also insert an extra rear derailer bolt to protect those threads. Make sure that when you put the bolt in the rear derailer thread only run it in until the end of the bolt is flush with the other side. If you have some exposed threads poking out they will get coated with powder and be a bear to unscrew.

I also run a bolt through the seat clamp bolts to make sure no powder gets into those threads.

If you have any questions let me know.
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Old 01-18-08, 08:56 PM   #10
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Yes, you are.

Any other insightful comments?
(mod edited) You don't know very much, do you?

I just had a frame powdercoated and I needed to remove some powdercoat on the dropouts which came off very easily using a file. You could use razor and sandpaper just as easy, but if you really want to make it simple you can use a special kind of paint stripper from a hardware store. I forgot the exact name of it.

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Old 01-18-08, 09:05 PM   #11
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I also insert an extra rear derailer bolt to protect those threads. Make sure that when you put the bolt in the rear derailer thread only run it in until the end of the bolt is flush with the other side. If you have some exposed threads poking out they will get coated with powder and be a bear to unscrew.
Ahhh, being a pack rat just paid off. I've saved practically every salvageable part from old bikes that I worked on, cleaned, sorted and stored in zip lock bags. So if I partially screw a bolt in every hole after the bead blasting, I've got most of it covered. I even saved old BB cups who's races were trashed. They all have a use now. Far out. This was just the kind of information I was looking for. Thanks.
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Old 01-19-08, 12:16 AM   #12
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re

Cool,

Concerning the BB cups; After you screw them into the housing remember to also mask off the center opening of the cups, you do not want the powder to get inside. I also will thread the cups into the housing maybe 3-4 threads then use the PC tape and cover the remaining exposed threads on the cups so that I can use them over again on the next powder coating job.

This is the type of tape you need to acquire:


ebay search for "Heat tape Powder Coating" will give what you need.

In a reply someone mentioned a solvent that will "cut" powder coating, it is called "MEK" and yes, it will soften up the powder coat, but beware, the stuff is pretty strong and you really don't want to mess with it.

Important: I am sure the shop you are using will know this..but ask just the same...make sure they are NOT using an "epoxy" powder. You want them to use a "hybrid mix or "polyester" powder. The Epoxy variety will break down under the suns UV rays and chalk over with time. The Hybrid and Polyester variety will not. Some shops will just shoot whatever powder they have in the color you want regardless of variety so be sure to ask.

Powder is awesome, you will love it.
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Old 01-19-08, 07:47 PM   #13
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I assume the BB cups need to be the metal variety, since the plastic might melt?
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Old 01-19-08, 08:12 PM   #14
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You don't know very much, do you?
Yeah, you don't.

Good thing I don't need to do much, you proved how much you know about powdercoating in exactly 2 posts in this thread for all to see.

How about powdercoating your bb threads? Seat tube? Headtube? Downtube braze-ons? Bottle cage braze ons? Are you going to remove the powder out of that as well?

You are doing the community a great disservice with your ignorance.

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Are you ********?
Also for future refrence, name calling is against the forum guidelines. Guess I was hoping for too much for someone that spends all their time in the BMX forum.

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Old 01-19-08, 08:28 PM   #15
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Try to keep it civil folks.
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Old 01-19-08, 08:34 PM   #16
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Yeah, you don't.

Good thing I don't need to do much, you proved how much you know about powdercoating in exactly 2 posts in this thread for all to see.

How about powdercoating your bb threads? Seat tube? Headtube? Downtube braze-ons? Bottle cage braze ons? Are you going to remove the powder out of that as well?

You are doing the community a great disservice with your ignorance.
How about no? It doesn't have any BB threads, and no water bottle cage, it's a BMX bike...

Also everything fit just fine without me needing to remove any powdercoat. Like I said the only powdercoat i removed was on the dropouts, that needed to be slighty filed down because I milled the 14mm axles down to 3/8 and they weren't fitting all the way in.



Quote:
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Also for future refrence, name calling is against the forum guidelines. Guess I was hoping for too much for someone that spends all their time in the BMX forum.
Cry me a river.

BTW you are still wrong, powdercoat is easy to remove.
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Old 01-19-08, 09:28 PM   #17
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Yes, no platic anywhere, it will melt like a mother.

I recently powdercoated some Shimano cranks for guy. He left some old pedals in the cranks to protect the threads....well the pedals were some older plastic variety, very hard and durable looking so I figured they would hold up...wrong.

They were in the over for 18 mim. at 400 degrees....melted them completely off, nothing remaining but the metal bearings and stem.

Live and learn....
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Old 01-19-08, 10:05 PM   #18
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Yes, no platic anywhere, it will melt like a mother.
Yeah, the powder coat guy on the phone stress that there should be no plastic or rubber. He asked twice about rubber, so me thinks he just had a recent incident on his mind.

Next time I'm going to have them sand blast the paint off. It's take all day today and I'm still not done. I knew the threading of the braze ons would be tough, but I didn't plan on the decals and then there is like a wax on the chain stays that repels the paint remover.
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Old 01-19-08, 11:26 PM   #19
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re

Sandblasting is the way to go. IT is cheap, usually around 25.00 to have the bike stripped clean and ready to paint.

some have stressed that you need to use "media" but in general the sandblast is fine. It may leave the surface of the tube just a bit more rough but the powder lays down very nicely over it.
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Old 01-19-08, 11:37 PM   #20
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BTW you are still wrong, powdercoat is easy to remove.
Your powder coating dude sucks.
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Old 01-20-08, 03:29 AM   #21
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Your powder coating dude sucks.
why? because I didn't tell him to mask certain things off?
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Old 01-20-08, 10:07 AM   #22
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unkchunk,
I have had one frame powdercoated. In the end it was worth it. But....

The powdercoater also did the bead blasting to clean/prepare the frame and I assumed that he would mask it properly as he said he had done a lot of bike frames. He was also recommended by a LBS.
I was not present for any of the process.

The bottom bracket was impossible for me to deal with since the overspray had covered the threads. I had to take it to a LBS to have the threads chased. Then all was okay.

Head tubes and seat tubes came through okay without masking.

Several other instances of overspray were such that I could fix them fine.

This is just my one experience.
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Old 02-19-08, 12:45 AM   #23
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Just to update. I finally got the frame back on Friday. Framesaver'ed it when I got home. Spent some of the weekend putting the bike together. Still have a little more to do and to get a brake cable for the front. But this is basically how she will look. I'm happy with it. Thanks for all your help.

Edit: Oh, and Wardrive's spare BB cups idea to protect the threads worked very well. Also used spare bolts to protect all the smaller braze-on threads. Almost too easy.
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Old 02-19-08, 08:34 AM   #24
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Ahhh, being a pack rat just paid off. I've saved practically every salvageable part from old bikes that I worked on, cleaned, sorted and stored in zip lock bags. So if I partially screw a bolt in every hole after the bead blasting, I've got most of it covered. I even saved old BB cups who's races were trashed. They all have a use now. Far out. This was just the kind of information I was looking for. Thanks.
+1

I did the same. Worked great. The items you've used to cover areas might get "sealed in" by the powdercoat. Don't just yank them off. Cut/score around the edges where you want the covering to make a clean break. Otherwise you risk some amount of over-flaking that might look bad. I also ended up filing off the rear drops. The original fit was tight and the powdercoat made the axles no longer fit. I like the recommendation to grind off the clamping areas outside the drops also.
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Old 02-19-08, 08:35 AM   #25
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And I WOULD cover any brake posts and downtube shifter bosses. Otherwise you'll have to file them clean later.
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