I have done lots of spray powder "welding" in the past..

We don't do it anymore..

We used that process to build up worn journals...
But the results were not always "reliable"..

We would have to really rough turn the journal at first..
Heat it up to red hot while spinning in the lathe..
Start the powder spray..
Hope it adheared..

After cooling then it was time to finish the journal...

9 times outta 10 as you were turning the journal..
most of the new surface would just end up peeling itself off and you'd be back to square one..:realmad:

So we tried grinding the surface instead...

Not much better..:realmad:

So we just stick to what really works..


Welding..(Tig actually)..

IMHO..
Spray powder "welding" sucks..

...zap!

 

Thanks for your personal opinion, based on personal experience! From what I've read on several pages the process is the best thing since sliced bread, so good to hear the other side. Thanks!

 

I am gonna have to agree with Zap. I picked up a setup a few years back at a show I was at and tried it a few times, and I was never satisfied with how it turned out. It never appeared to stick real well. I tried it on a few shaft journals and as Zap mentioned alot of times it would just peel off as you tried to turn it.

 

I spent a lot of time searching this morning and found that the process is widely used in industry. Seems the process has been upgraded in the past few years and now offers excellent results in many applications.

Only problem is in a couple of hours of web surfing I didn't discover one single company that offers a torch or equipment for sale online! Couldn't even get very many hints about who manufactures equipment. Dozens sell the powdered metals. I have no idea what's going on with that but it looks like the DIY equipment is unavailable. Thanks for feedback...

 

eutectic castolin, eutalloy, terodyn, roto-tec, metallizing, are some search words. theres usually at least 1 torch set on ebay which is where i got mine (havent used it yet though).

 

My only experience with spray powder welding is I have reworked some cast iron pieces that were previosly done with powder welding. From what I have seen it seemed to adhere to the cast iron quite well. It was very difficult to grind off. The company who had previously done the work on the piece specialize in this type of build up work. Maybe there is a trade secret that the common welder, or even advanced welder is not aware of. Like I said , this was just my experience, and it seemed to work well.

 

Our shop purchased a Victor brand outfit a couple of months ago. It was used to hardface the cutting edge of a scraper bar that cleaned a conveyor belt. It worked but from my view I thought it was slow.

 

From what (very) little I know about these things, there are two different kinds.

One is OA that melts a powder and sprays that out of a nozzle.. The other is a wire feed arc process that melts wire (or actually two wires if I remember right) and sprays the molten metal out of a nozzle.

Which one is which in terms of what seems to have worked and what didn't?

 

From what I found searching the web there are at least 5 different processes, all somewhat similar in some ways but with major differences in machinery or process. Seems like much research has been done and the processes have evolved into a very reliable and effective solution. However there are few who have extensive experience, so failure rates can be high in some cases. Others are high dollar shops that perform the process and aren't giving out any secrets.

I finally tracked down one torch outfit from Victor but it seems to be little more than oxy/acet torch with a hopper and oxy feed of powder. For some reason the various setups aren't widely available, so maybe the few are keeping a closed shop or whatever. Looks like I may have to contact the manufacturers beyond viewing web pages.

Good question on which process or equipment worked, and which did not. Just like anything else, brand names and level of exerience of operator would help, too. Thanks for the feedback so far!

 

I've never done it, but I've known about it from my days as an inspector when we went through training for coatings.

Anyway, I found this:

http://www.thermadyne.com/stoody/literature/pdfs/js-100.pdf

 

Thanks, Mac, that Thermadyne Victor VPT100 is the one I found! Very basic but might work in some applications. I think I could almost build one like that.

 

Instead of flame and heat powder spray, my lab purchased a cold-spray outfit. This techncique uses supersonic gas flow velocities to impact/fuse powdered metals into the work piece.
Here is the vendor site: http://www.supersonicspray.com/index.htm
Problem is - my lab has not installed this yet - so no experience to report. In any case, it looks far more expensive than the Thermadyne Victor VPT100 reported earlier.
Anyway - if we do get it operating, I'll report back.

Rick V :waving:

 

I dunno, Rick, maybe I'm easily wowed, but that setup is downright amazing to me! Probably about $50,000 over my $200-$300 budget but it's got to be pretty slick. Let us know what happens.

I need one of the processes that only heats the treated part to 300-500 degrees, as they're heat-treated components, specifically camshafts. Unfortunately only the cam's lobes are heat-treated, so the bearings consume themselves even when installed in an aluminum head! The problem may be contributed to by an archaic oil fitration system, but it's too late to change that when you discover a wiped cam. So I need to be able to restore these cams, and also install superior oil filtration, with cam resurfacing being the first step. Cheap is a major issue, as usual

 

Woah...!!!!

If you want to rebuild camshafts..
I'm really not sure if spray powder is the way to go..
Maybe it is..
Maybe not..

You may want to re-think your process...

Myself personally..
I would not do it..

But thats just me..

...zap!

 

AZEDGE, Almost all of the setups I have ever seen were built just like the Victor. If you only have a $200-$300 budget you are gonna be hard pressed to find a dependable setup that will work with good results for what you are attempting. I could be wrong, but even the spray torches would heat the material over 500 degrees. I don't know how you could get a strong bond at that low of a temp. I realize you are attempting to not ruin the heat treating while building up, but I would think you will still have to have it reheat-treated after build up and machining. Which leads to another question, how do you plan on remachining the shafts after you find a way to build them up? I think the main drawback is going to be price. I don't see how you can do it, and keep your price reasonable.

 

All these camshafts I'm concerned with run in aluminum, of all things, with no other bearing. The 'bearings' are usually pretty pounded too. Hoping to 'weld' up the cam's bearing surface which would of course enlarge it, and then turn surface down true, and bore/ream the aluminum it runs in to fit. Might bore aluminum enough to fit a bronze bushing also, if it can be done. Many of the cams are no longer available, and just an aftermarket replacement can run $300, and the aluminum bearing journals would still need work after that even with a brand new cam.

I would do a couple for my own use and analyze the problems, then if it works out satisfactorily and is affordable, offer it as a service. I appreciate the excellent advice, and the cautions. It's something I'm looking into, not something I'm committed to. Might work, or might not, ya know how that goes, but thanks to all for the help!

 

Straying from the topic a bit but what engine are you working with. There is tooling available and shops set up to line bore the cam journals and put insert bearings in many of these overhead cam engines.

 

Thanks, tresi. I'm familiar with the various machine processes and other 'fixes' but for many cost is a consideration. These are vintage motorcycle engines and it's hard to justify a $1,000 bill to repair the cam on a bike that's only 'worth' $500-$1,000. There are aftermarket cams, and needle roller bearing inserts available, and then add machining and all the rest and it's just not practical or affordable for the average broke guy! We try to keep them running as cheaply as possible, so I'm researching this possible solution to a common problem.

If the cam can be easily and cheaply built up then it's only a matter of a local machine shop tossing it in the lathe and turning it down some, and maybe cleaning up the bore in the head.

 

Well, If you have enough cams to experiment with I seen a spray weld set up on E-bay a day or so ago. I seen several of these on ebay over the years. The industrial supply houses such as MSC or McMaster-Carr have them. If your talking about an iron cam and an iron poweder the machine shop will most likely have to grind it down rather than turn it.
If you happen to have a steel core cam couldn't you tig it up a little bit at a time stopping to let it cool before the lobes got too hot?

 

and just an aftermarket replacement can run $300, and the aluminum bearing journals would still need work after that even with a brand new cam.

As a suggestion, how much of a day's work are you willing to do for $300? That would not cover one full day where I am. How many of these can you do in a day?

 

Well, let me see if I can make it at least sound sensible. There's a whole bunch of dead engines or cylinder heads used in these vintage cycles. These bikes are sought after by many of us nutballs just because we like the old things, ya know? Makes no sense really. They're used trail riding, MX, raced in vintage events, daily drivers, dual sport etc. One of the real weak points is the cam and bearings, or lack of bearings to be more precise.

I'd like to find some way to salvage the cams, because new replacements are real pricey. There are needle bearing conversions available, but these things ran for thousands of miles with the iron [?] cam running in the plain aluminum 'bearing' bore in the head. The needle bearing cams really get up there in price, compared to the value of the bikes.

I'm hoping to discover a method of restoring the camshaft itself at least to original specs. Along with that I'm looking into a cheaper pressed bronze bushing instead of needle rollers for the cam bearings. That shouldn't be rocket science to do, I hope, and should be pretty cheap too. I haven't got much to invest in the cam resto part of it, so that's where the $300 reference came from, for the powder torch or whatever. Once I've got that it's little more than straight labor to do the job.

I'm not looking at heavy deposition of metals, just a deep enough coat to get slightly beyond the original surface levels. Then a quick turn in a lathe to true up the bearing journals to original diameter, and bore the head and press in a bronze bushing. After doing a few it seems that it would get down to a couple of hours of work to weld up, turn down, bore head, press bearing and call it good. A friend just bought an old LeBlonde lathe he's restoring, so he will do the machining. I'm looking at the cam welding part of it, and together we can figure out the bushing?

With this vintage stuff in many cases there are no more cams, or no more heads or both, and if there are they're priced like Ferrarri parts. So the plan is to help all the other screwballs that like to waste time on these great old bikes and keep them on the road or track or trails. For some reason we're mostly broke, along with being slightly crazed in the mind. Thanks for all the great replies so far, guys. I hope it makes more sense [?] now....

 

Are the journals in the head split or solid? If solid how close are the nose of the cam lobes to the diameter of the cam bearing journals? You might be able to fix this without welding at all. If you have split journals in the head couldn't you get the caps cut a few thousands and then line honed or reamed? Then grind the cam journals to fit, assuming that this engine has enough adjustment to get the valve lash right. If you take the minimum cut required to clean up the damage it shouldn't change the lash much.
If you have solid journals in the head and you're planning to make bushing insert anyway couldn't you make the I.D. of the bushing enough undersize to make up for the damage on the cam and then again grind the cam to fit? This assumes that the nose of the cam lobes will go through the bearing inserts. You will have to make the bushing a press fit. After driving the bushing in the I.D. will be smaller than the machined size so line hone or ream the bushing after installation. So make sure your bushings are installed and sized before reworking your cam.
By the way how worn is your cam and journals right now. Good luck and be sure to post pics in the projects section when you get this up and running.

 

I'm not looking at heavy deposition of metals, just a deep enough coat to get slightly beyond the original surface levels. Then a quick turn in a lathe to true up the bearing journals to original diameter, and bore the head and press in a bronze bushing. After doing a few it seems that it would get down to a couple of hours of work to weld up, turn down, bore head, press bearing and call it good. A friend just bought an old LeBlonde lathe he's restoring, so he will do the machining. I'm looking at the cam welding part of it, and together we can figure out the bushing?

I'm not trying to knock ya, but it seems like you think this is gonna be simpler than it will be. You won't be able to just throw a cam in an old Leblond and turn it down. To start with the journals will need to be ground, and if he is restoring it then the tolerances are probably not real tight on it to start with (I'm guessing). A couple hours will not start to touch the amount of work this will take. To build up the cam, and then finish it to size is not going to be a quick process. Then your bushings have to be made, then your bore the block. I am assuming that you haven't done machine work before, but it will take you as long to set up for the machining process as long as it does to perform the work in a lot of cases especially since things like this need to be DEAD on as far as centering goes. I am guessing you'll be looking more like 2-3 days continuous work rather than a couple hours.

If you are gonna install bronze bushings then you don't need to build up the journals. All you need to do is grind the existing journals just enough to true them up then turn your bushings (bearings) undersized to fit. Just like crankshafts are done regularly. and if you are going to build up the journals and refinish them then just build them up larger than original, and bore the block a few thousandths larger to fit and you don't need bushings. Just some things to think about.

 

I should add to my last post post to make it more clear. I said to to intall and size your bearings before reworking your cam. To avoid either reaming or boring the bushing twice or grinding the cam twice rough grind the cam to remove any damage. This will give you a size to shoot for on your bushing. Install the bushings and finish the cam to fit. You can finish the cam before installing the bushings but then you'll then have to size the bushings to the cam.

 

Are the journals in the head split or solid? If solid how close are the nose of the cam lobes to the diameter of the cam bearing journals? You might be able to fix this without welding at all. If you have split journals in the head couldn't you get the caps cut a few thousands and then line honed or reamed? Then grind the cam journals to fit, assuming that this engine has enough adjustment to get the valve lash right. If you take the minimum cut required to clean up the damage it shouldn't change the lash much.
If you have solid journals in the head and you're planning to make bushing insert anyway couldn't you make the I.D. of the bushing enough undersize to make up for the damage on the cam and then again grind the cam to fit? This assumes that the nose of the cam lobes will go through the bearing inserts. You will have to make the bushing a press fit. After driving the bushing in the I.D. will be smaller than the machined size so line hone or ream the bushing after installation. So make sure your bushings are installed and sized before reworking your cam.
By the way how worn is your cam and journals right now. Good luck and be sure to post pics in the projects section when you get this up and running.

Somehow my replies a couple of days ago got lost in cyberland! So: YES! Great idea, Tresi! There's no need to weld up at all. Two different models, one with 2 piece head, more common 1 piece head. It's designed that the came slips in place from one side only and fits in aluminum bearing journals. So yes, I can turn down crank, press in bronze bushings, then finish hone cam or finish ream bushings for a perfect fit.

And yes, Hammack, more of the same good advice! I have little machining experience but a friend of mine has 40+ years worth so hoping for the best there. I don't expect it to be easy the first couple of times, but once a few are done it should get down to a fairly quick process I think. All the setup will be known, and they're all the same cams and heads.

Bunches and bunches of thanks, guys, one and all, as you really made all of this much simpler than I had complicated it into haha! Should be able to do the whole process way more easily plus save all that money I'd have spent on a spray welder! Thanks again, guys!!!