Setup for sandblasting/painting bike frames

[pedal_power]

Firstly (before I shamelessly pick your collective brain), this being my virgin post on this forum, I should like to say hello to all, and thank you in advance for any information shared.

So to cut to the chase - I do a bit of hobby bike framebuilding/refurbishment, and have reached the stage (with half an eye on the possibility of turning it into a business in future), where I'd like to have control of the final process, ie paint.

I've had a good trawl of the various forums and have picked up an awful lot of useful information (so I'm already indebted), but due to the majority of info out there pertaining, it seems, to car refurbishment, where you're obv. talking relatively large/flat surface areas vs a bike frame, I'm somewhat struggling to extrapolate the specifics of what's relevant to my needs - if that makes sense.

So I have a few specific question, but any info gratefuly received -

1) Sandblasting - would something like this - http://www.ebay.co.uk/itm/SSG8-Sand...otn=4&po=LVI&ps=63&clkid=3704169699351951910I - be appropriate or would I need a pressurised pot sandblaster? If the former, what size air compressor should I be looking at?

2) Similarly re. paint gun, what would be an appropriate size, HVLP vs LVLP - airbrush even?? And can it be run off the same compressor? Do I need a different gun for the primer and colour/clear? (very basic stuff i know)

3) I live in possibly the wettest/dampest area of the uk - am I asking for trouble attempting this without some form of air cooling system? (filters would obv be a bare minimum requirement)

4) What sort of paint would be suitable for bike frames? Ideally it needs to be something that goes on quite thin as I'd like to maintain detail/lug definition etc. With that in mind does anyone have any experience of this stuff - http://www.autoaircolors.com/ - water based, available in very small quantities so sounds ideal but how durable is it?

So all pretty basic stuff as you can see. There were a couple of other things but my mind's temporarily blanked, so I shall leave it there for now and errr.........over to you

 

[brightspark]

the gun on ebay is a suction gun ideal for a few minor parts to be cleaned the minimum would be a pressure pot using a 3mm jet and a 14cfm compressor preferably belt drive u would need a quite large cabinet for blasting the pushbike frames or get a small shed to blast in to contain the media

 

[stormin]

1) I've still got one of those blast guns somewhere, you could have it for the rice of postage but I've nothing against you, so probably best you don't have it. Get a pressure pot 10 or 20 gallon and expendable abrasive for blasting the frames. For all the other bits build yourself a small cabinet. A 205 litre oil drum is ideal for most other bike bits, there's a build thread of one on here recently, still use the pressure pot though not a suction gun they're too inefficient when used with a small compressor and the oil drum design isn't great for media pick-up.

2) Re spraygun I'm not an expert nor have I really done a high quality paint job but Ive got by with a simple suction gun for primer and top coat, mostly with synthetic for years. similar to this one and cheap http://www.ebay.co.uk/itm/200598289278?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

3) I take it your in Manchester as well then, wettest area of the U.K. ? As most bike bits are fairly small and compressor usage times are likely to be quite short heating of the air and cooling/drying may not be too much of a problem. Simplest method may be as shown in the guides on here, with a metal air line run round the garage with a drop leg or two to collect moisture, use that in combination with a decent filter regulator at the end and it should be fine for all but the highest quality of jobs.

4) re paint I'm no expert other are more qualified but I would avoid powder coat. Seems to be rather popular in place of the old stove enamel coating of bike frames etc but I hate the stuff, once it's damaged it's near impossible to do a nice repair and it seems trerrible for trapping moisture underneath to encourage rust and further peeling.

 

[pedal_power]

Hey thanks for the swift replys - all good.

@ Brightspark - I thought this may be the case re the sandblaster, but was hoping I could get away with something smaller/cheaper for bike frames but I see now this isn't possible.

So 14 cfm minimum - would that be displacement (which seems to be the only figure most manufacturers give) or FAD? How would you rate something like this - http://cgi.ebay.co.uk/ws/eBayISAPI....68484185&category=22662&_trksid=p5197.c0.m619 - not great quality I'm guessing at that price (and certainly not German built despite the crafty branding) but would it do the job for me? Ideally I'd go for a Clarke SE16C10 but at just under £500 that's over my budget really. Otherwise I guess it's try and pick up something second hand.

ps I'll be using a blast cabinet.........if I get that far

 

[pedal_power]

1) I've still got one of those blast guns somewhere, you could have it for the rice of postage but I've nothing against you, so probably best you don't have it. Get a pressure pot 10 or 20 gallon and expendable abrasive for blasting the frames. For all the other bits build yourself a small cabinet. A 205 litre oil drum is ideal for most other bike bits, there's a build thread of one on here recently, still use the pressure pot though not a suction gun they're too inefficient when used with a small compressor and the oil drum design isn't great for media pick-up.

2) Re spraygun I'm not an expert nor have I really done a high quality paint job but Ive got by with a simple suction gun for primer and top coat, mostly with synthetic for years. similar to this one and cheap http://www.ebay.co.uk/itm/200598289278?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

3) I take it your in Manchester as well then, wettest area of the U.K. ? As most bike bits are fairly small and compressor usage times are likely to be quite short heating of the air and cooling/drying may not be too much of a problem. Simplest method may be as shown in the guides on here, with a metal air line run round the garage with a drop leg or two to collect moisture, use that in combination with a decent filter regulator at the end and it should be fine for all but the highest quality of jobs.

4) re paint I'm no expert other are more qualified but I would avoid powder coat. Seems to be rather popular in place of the old stove enamel coating of bike frames etc but I hate the stuff, once it's damaged it's near impossible to do a nice repair and it seems trerrible for trapping moisture underneath to encourage rust and further peeling.

Useful advice Stormin - thanks.

Right I think I get the picture re. the sandblast gun - leave WELL alone. Ah well looks like a pressure pot it is. Offer appreciated all the same (I think he he)

I'm situated in deepest, dankest west wales - up in the mountains, so whatever happens to be coming over the atlantic/Ireland tends to defecate right on us. Manchester may well be wetter, but having lived here most of my life, I struggle to imagine that such a place could possibly exist. It has it's positives though - we've got a pretty view.

Edit - and re. the paint, that stuff I linked to isn't powdercoat is it? I tend to agree with your sentiment - I far prefer enamel coating on bike frames as a rule, from a pure aesthetic perspective if nothing else. Chips rather too easily though.

 

[stormin]

Edit - and re. the paint, that stuff I linked to isn't powdercoat is it? I tend to agree with your sentiment - I far prefer enamel coating on bike frames as a rule, from a pure aesthetic perspective if nothing else. Chips rather too easily though.

No that paint isn't powder coat, I was just giving my personal preference that I don't like powdercoat in fact anything else would be preferable.

I think the main reason powder coat is used so widely is that a huge thickness of coating can be applied in one hit without runs, hence it's a cheap way of doing things.

Having to employ someone to build up a decent paint finish in a large number of coats with some skill is quite expensive in comparison.

 

[bod]

Hi Pedal,
I've just joined because I'm looking at getting a TIG for frame welding so maybe I could pick your brains too.
Anyway, I work for a paint company and have access to lots of expensive paint toys; I've sprayed about 20 frames and they're not the easiest thing to spray, ideally you'll need a small HVLP gun, they're often sold as touch up guns, to get in between the stays by the BB and around the back of the head tube.
Spray guns tend not to use much air so if you've got a big enough compressor for a shotblaster then you'll be fine. There's a woman in Australia who makes frames under the name Little Fish who uses an air brush to get very thin coats but she must have the patience of a saint and the gloss isn't very high.
At work we use seperate guns for primer, water based paints, solvent based paints, metallics and clearcoats but that's partly to prevent cross contamination and also because certain guns atomise the paints differently even though it doesn't seem to make all that much difference as far as I'm concerned. If you're starting out one gun will be fine as long as you have different nozzles for the different paints you're spraying (the technical data sheet should have that kind of info).
You won't need any cooling but you'll definitely need heat, some 2K paints need heat to cure (it accelerates the cross link polymerisation don't you know); some kind of spraying area free of all dust would be pretty important too as paint sucks dust out of the air which forms an inclusion that can't, generally, be sanded out with going through the layer. We've got a cool ionizing gun that fires negatively charged particles at the work piece and stops this happening. Spraying is sensitive to humidity and is more of a problem for water based ones but again this should be on the TDS.
As for shot blasting, I've tried it with one of the guns you linked to and it took ages, far better to use a sander and paint stripper. I've got some from work that is brilliant, not sure what it's made up of, but it's as thin as water so I need to find or make a tank, it'd save me hours of prep.
As I'm sure you've read, spraying's a bit of a misnomer, it should be called sanding or something! Preparation is absolutely key, the paint job is only as good as the surface it went on.
Anyway, I could bang on about this stuff for hours do feel free to ask any more questions and I'll do my best to help with the bits I've had experience with.
Matt

 

[pedal_power]

Hi bod - just the sort of thing I was hoping for so muchly appreciated. Please do bang on - this stuff is all new to me so I'm all ears.

I am aware of the Littlefish website as it happens - that's actually what prompted me to enquire as to the suitability of the autoair paint. Genuine admiration for the way she's gone about documenting the whole process - don't think I'd have either the time or inclination.

Re. sandblasting - my primary use for it would be removing light (post flux soak) rust on newbuild frames and getting into the nooks and crannies that are inaccessible with sanpaper - is there any other prep work necessary on bare metal prior to applying primer if it's been well blasted?

And just a quickie re. guns - is hvlp more suitable for bike frames than lvlp?

Heat is something I've thought about, and there are plenty of resources online for diy ovens, but ideally it's something I'm hoping I can avoid, although, as stated in my op, I may have no choice in the matter considering the local climate. Any advice on which paints are suitable for 'heatless' drying and which are absolute no gos?

Oh and please feel free to pick my brain, although I'm afraid (and this admission may be enough to get me put in the stocks 'round these parts ) I've never so much as even picked up a welder in my life (something I hope to remedy at some point) - all my frame work so far is brazed (brass and silver) so i prob won't be much help. There are a few recent threads on here documenting welded framebuilds though, so those are prob the people to tap up for advice. That said, I'd be more than happy to share any general framebuilding info if/where appropriate (must be said I'm by no means an expert - although these things are all relative of course)

 

[rtbcomp]

I always recommend customers clean blasted items with a thinners compatible with the paint they're going to use.

You're bound to get a light dust residue and greasy fingermarks. Tack cloths are a good idea too.

 

[pedal_power]

I always recommend customers clean blasted items with a thinners compatible with the paint they're going to use.

You're bound to get a light dust residue and greasy fingermarks. Tack cloths are a good idea too.

Ah yes I neglected to include 'some sort of de-greaser after blasting' in there. I was thinking more in terms of the surface finish left by the blasting - my assumption is it's good to take the primer?

 

[rtbcomp]

The surface finish left by J-Blast Supafine is suitable for a primer.

 

[bod]

Yeah, Little Fish is pretty inspiring; I didn't realise it had moved to a blog, she's producing some really nice stuff, I'm quite jealous.
Sandblasting makes a really nice key for any primer but the spot blaster I've got takes ages and refilling the pot time and time again is a pain. Almost any frame shouldn't have any corners you can't get to with sandpaper and the rust comes off very easily but it's probably best to have a play and see what works for you. I've not had a problem but once It's stripped and washed (with water to get rid of the stripper) I bake it in the oven to make sure all the water has evaporated then sand any rust spots (while wearing butyl gloves so the grease from my hands doesn't get on it) then wipe with thinners before quickly applying epoxy primer to seal it although any primer should be fine.

We exclusively use HVLP here although I'm not sure why we don't use LVLP, I'll have a word with our production guys later and see what they say. In fact I've just found one stuffing his face with a bacon cob and the bits I could make out was they need to be kept much cleaner and have a harder edge so blending will be harder. Sounds ok if you've got a smaller air supply and you don't mind keeping them really clean. On the upside, they spray slower so you can control the film thickness better and there'd be less overspray.

Most paints have a minimum temp they can be applied at along with other factors like humidity so you'll need some control over them, Suzy at Little Fish built a nice simple "booth" although she probably won't have much of a problem with weather like today... Shame you're not nearer or you'd be welcome to have a play in our booth, if you could bring your torch and bottles you'd make me more excited than a kid at Christmas too!

Unfortunately my experience only extends to our own paints though so I can't be much help there. I know Imron is the gold standard for custom builders and painters in the US and I have used House of Kolor which are very nice, not sure about pricing. I've read some things about isocyanate containing paints on here and while I know familiarity breeds contempt they're not all bad, as long as you have the correct mask and sufficient extraction it shouldn't be a problem, we have to have health surveillance twice a year and there's been no issues so far. They also produce very good results unfortunately.

I've been thinking about TIG only because I could use it for other stuff but frame making is my main reason for getting it, how much did your set up cost? The main problem I can see with would be getting hold of gas bottles, I've heard it tricky for the amateur builder. Unfortunately I can't store them at work either as I'm in enough trouble as it is with all the bikes and frames all over the place...
Are you building with lugs or do you have experience with fillet brazing too? I quite like the idea of going down the bi-laminate route so I can customise the geometry and not be restricted by lug sets. Any pictures or what you've built? A bit of gratuitous frame pron never goes amiss!

Matt

 

[pedal_power]

The surface finish left by J-Blast Supafine is suitable for a primer.

Thanks rtb - duly noted.

 

[pedal_power]

Thanks again Matt - all useful stuff. I've replied below (can't get the multi quite to work for some reason)

Yeah, Little Fish is pretty inspiring; I didn't realise it had moved to a blog, she's producing some really nice stuff, I'm quite jealous.
Sandblasting makes a really nice key for any primer but the spot blaster I've got takes ages and refilling the pot time and time again is a pain. Almost any frame shouldn't have any corners you can't get to with sandpaper and the rust comes off very easily but it's probably best to have a play and see what works for you. I've not had a problem but once It's stripped and washed (with water to get rid of the stripper) I bake it in the oven to make sure all the water has evaporated then sand any rust spots (while wearing butyl gloves so the grease from my hands doesn't get on it) then wipe with thinners before quickly applying epoxy primer to seal it although any primer should be fine.

I'm thinking of it from a time saving perspective as much as anything tbh, although those BB/seat stay junctions and in and around braze ons/drop outs really are a pain to sand by hand.

What sort of oven do you use? Commercially built or diy jobbie?

We exclusively use HVLP here although I'm not sure why we don't use LVLP, I'll have a word with our production guys later and see what they say. In fact I've just found one stuffing his face with a bacon cob and the bits I could make out was they need to be kept much cleaner and have a harder edge so blending will be harder. Sounds ok if you've got a smaller air supply and you don't mind keeping them really clean. On the upside, they spray slower so you can control the film thickness better and there'd be less overspray.

Most paints have a minimum temp they can be applied at along with other factors like humidity so you'll need some control over them, Suzy at Little Fish built a nice simple "booth" although she probably won't have much of a problem with weather like today... Shame you're not nearer or you'd be welcome to have a play in our booth, if you could bring your torch and bottles you'd make me more excited than a kid at Christmas too!

Unfortunately my experience only extends to our own paints though so I can't be much help there. I know Imron is the gold standard for custom builders and painters in the US and I have used House of Kolor which are very nice, not sure about pricing. I've read some things about isocyanate containing paints on here and while I know familiarity breeds contempt they're not all bad, as long as you have the correct mask and sufficient extraction it shouldn't be a problem, we have to have health surveillance twice a year and there's been no issues so far. They also produce very good results unfortunately.

I've been thinking about TIG only because I could use it for other stuff but frame making is my main reason for getting it, how much did your set up cost? The main problem I can see with would be getting hold of gas bottles, I've heard it tricky for the amateur builder. Unfortunately I can't store them at work either as I'm in enough trouble as it is with all the bikes and frames all over the place...
Are you building with lugs or do you have experience with fillet brazing too? I quite like the idea of going down the bi-laminate route so I can customise the geometry and not be restricted by lug sets. Any pictures or what you've built? A bit of gratuitous frame pron never goes amiss!

My setup is one of these - http://www.ebay.co.uk/itm/CLARKE-OX...Home_Garden_PowerTools_SM&hash=item2ea65299c0 - (which I was lucky enough to get for £150). No need to go down the acetylene route - I just use a standard 6kg orange cylinder propane (£15 - £20 and lasts forever, and with the right size tip you'll have no problem brazing silver or brass (lugs or fillets) and of course it's safer/cleaner/cheaper/more readily available - the only downside is, due to it's lower temperature vs acetylene, it does tend to guzzle the oxygen, so you prob don't actually save much overall) and boc rental oxygen - I use smallish cylinder size x atm (I'll upgrade in future) which is about £30 a fill inc service charges plus £80 a yr rental (that's off the top of my head so may be slightly out) - so yeah not cheap but the only option really unless you can find somewhere that offers single charge non rental, but there prob still wouldn't be much in it, and if you're using propane and plan on building a number of frames, you'll likely be refilling fairly regularly, so rental is the way to go.

So in terms of setup cost, a decent welder will prob cost you more, but the running costs of brazing are greater (especially if you decide to lug braze with silver), also I think it takes longer to become a competent welder than it does a brazer - lugs in particular provide quite a safety net, and of course your raw work isn't visible in the way it is with welding.


The main thing welding has over oxy-gas though is, as you point out, it's versatility - the value of having the capability to knock together bits of jigging etc can't be overstated. That said, you'd still need (at least access to) an oxy-gas setup for all the smaller braze on jobs, and welding frames requires a full frame jig (something you can obv build, but it's still gonna cost) whereas you can get away without one with lugs/bi laminate (full fillet needs a jig) by pinning the joins pre braze. My first frame was built using the most rudimentary jigging you could possibly imagine, pinned lugs then brazed free hand, and it turned out remarkably well considering. Still ride it today even though it's just plain gauge chromo and weighs a ton. I've become rather sentimentaly attached.

I've got some pics of my latest build (which is mainly fillets/bi-lam with a lugged BB shell - I don't have a full jig so can't do full fillet which is where I want to be ideally) but don't have them up online yet. I'll link them here when I do though.

ps what sort of frames would you be looking to build?

 

[bod]

Well, I've only experienced light rust that comes off with a quick rub of 120 or 250 grit paper and the blaster is a pain to set up, run and tidy up after (I climb in a large plastic bag with the frame and then empty the bag out again to reuse the shot) but it sounds like you're having a harder time of things than I have. Freshly blasted steel give loads of grip to the primer (although you'll need a reasonably high film build to cover the rough surface) so if you're set up to do it that way it would be best.
We've got a spray/bake oven so you spray it, press a few buttons, come back in a few hours and it's done, I'm pretty lucky really. Having unlimited free paint, sandpaper, special effect paint, colour matching is pretty cool too.

I've heard that it's hard to get acetylene over her, America seems to have much better access to manly stuff and at much cheaper prices too. They don't make it easy for us so they?
Ultimately I'd like to build a titanium frame so a TIG would be essential but that's very likely just a pipe dream, getting good enough to weld ti to a decent standard would take year I imagine, I've seen a professional builder's attempt in his gallery and the welding looked awful. You can't beat a good lug for pure aesthetics though, Peter Weigle and the like seem to have that down pat it's just not the kind of bike I'd ride (I'm more of a mountain bike rider really), even though I'm obsessed with bikes I still, generally, think of them as tools; making my own would be the ultimate.
Anyway, some pics of your builds would be really interesting, I definitely keep an eye out for them.
Matt

 

[pedal_power]

Couple of rudimentary pics (picassa only I'm afraid) - https://picasaweb.google.com/107740751006559184282/October272011?authuser=0&authkey=Gv1sRgCNe3vMDlvKCjwgE&feat=directlink

I'm terribly disorganized/lazy when it comes to photo documenting the build process etc so these shots are all I've got atm.

Fairly standard road geometry with a bit of curvy stay action. All brass fillet brazed bar the BB shell which is lugged. Just needing a lick of paint.

 

[pedal_power]

Well, I've only experienced light rust that comes off with a quick rub of 120 or 250 grit paper and the blaster is a pain to set up, run and tidy up after (I climb in a large plastic bag with the frame and then empty the bag out again to reuse the shot) but it sounds like you're having a harder time of things than I have. Freshly blasted steel give loads of grip to the primer (although you'll need a reasonably high film build to cover the rough surface) so if you're set up to do it that way it would be best.
We've got a spray/bake oven so you spray it, press a few buttons, come back in a few hours and it's done, I'm pretty lucky really. Having unlimited free paint, sandpaper, special effect paint, colour matching is pretty cool too.

I've heard that it's hard to get acetylene over her, America seems to have much better access to manly stuff and at much cheaper prices too. They don't make it easy for us so they?
Ultimately I'd like to build a titanium frame so a TIG would be essential but that's very likely just a pipe dream, getting good enough to weld ti to a decent standard would take year I imagine, I've seen a professional builder's attempt in his gallery and the welding looked awful. You can't beat a good lug for pure aesthetics though, Peter Weigle and the like seem to have that down pat it's just not the kind of bike I'd ride (I'm more of a mountain bike rider really), even though I'm obsessed with bikes I still, generally, think of them as tools; making my own would be the ultimate.
Anyway, some pics of your builds would be really interesting, I definitely keep an eye out for them.
Matt

Hmmm I'm rather jealous of that spray booth setup. I'm planning on bodging something up from some alu studding/galvanized sheet and a couple of electric heater filaments and a fan. Doesn't need to be huge so shouldn't set me back too much.

Re. acetylene - as far as I know a majority of it in the US is produced at one refinery, and I read somewhere there was an explosion fairly recently that caused a national shortage. Don't know how it effected the UK though. BOC supply the stuff though - that's about as far as my knowedge extends.

Couple of links for your titillation -

http://www.blackcatbicycles.com/ - very nice fillet steel mountain bike frames. Planning something similar for my next build.

http://www.blacksheepbikes.com/ - titanium 'frankenstein' frames.

 

[bod]

Blimey, you've been doing this a while then? Very, very nice! Love the seat stays, kind of Hetchins but also modern and fast looking somehow. Any frame I made would have a fastback seat clamp too, the clean lines just make it flow so nicely. Anyway, enough gushing...

Those Black Cat frames have some amazing paintwork, I'm guessing it'd all be done with spray masks and airbrushes, we've got an airbrush but I've yet to use it much. What I'd really like is a plotter so I can cut the designs out accurately, masking is deceptively hard (to me at least).

Your booth set up sounds fine, it doesn't need to be too complicated, just something to keep the dust out, hold a bit of heat in and get some ventilation. Dust would be your biggest obstacle to a perfect finish, I've heard of some people spraying water on the floor to keep it down.
It really is a shame you don't live closer, it'd be pretty cool to see the process after reading so much about it. Oh well, guess I'll have to keep saving for that Dave Yates frame building course...

 

[pedal_power]

Ach meant to reply sooner but been a bit busy (not building bikes/spray booths though sadly)

I've decided to give the sandblaster a miss for the time being - found a guy locally who'll do it fairly cheap and saves me spending a wedge on a big compressor. Still would like to do the paint myself though. That HVLP gun you mention you use - what size compressor would it require?

Yeah I generally prefer fastback stays, and was the only option I had really due to the angle created by the curve of the stays. Mitering those stays was a ****** though - took me an aaaaage to get the length and angles the same (serves me right for doing it by hand) - not sure it's something I'll be attempting again in a hurry.

If you're seriously considering the Dave Yates course, I'd urge you just to get yourself an oxy setup (you can pick em up second for under £100 on ebay) and dive in. Really while you're hanging around 2 yrs waiting for your turn, you could have half a dozen frames under your belt (money permitting). Sure there are benefits to learning from an expert, but equally there's something to be said for doing it the hard way, making the mistakes. However time consuming and frustrating it is, it's always hugely rewarding. And he only teaches brazing anyway (not meant as a diss, but you seemed intent on welding?).

I've always wondered why there aren't more people teaching framebuilding - I suspect a few more will pop up over the next few years though.

 

[500e]

Simple booth with damp floor try & pump the heat in & keep a slight + pressure internally, don't forget to filter incoming air