View Full Version : What is "acceptable" gap when it comes to welding frame tubes? (Fit-up)

02-25-2016, 5:34 PM

Read the posting policies, did numerous searches, could not find anything specific on this. Please excuse me diving in the deep end.

I wonder if you help clarify matters for me, I have a bit of a disagreement with a frame builder on some welding they've done to my frame.

•*What is "acceptable" gap when it comes to welding frame tubes? (In this case it is many just cross members).

My understanding is that there should be a good fit all around the join, bevelled off to allow both tubes to fuse together. Many 1/8" at most.

How much of a gap can you safely tolerate, and around how much of the join? To me, this guy is welding weld to weld to fill gaps like it is filler.

It's 1" steel tube and about .12" or .15" wall.

Much appreciated.

02-26-2016, 12:56 AM
Joining a tube at 90 degrees for the sake or argument.

Tubes should fit really tight.Both ends should of been prepped with a fish mouth to sit tightly

02-26-2016, 7:37 AM
Joining a tube at 90 degrees for the sake or argument.

Tubes should fit really tight.Both ends should of been prepped with a fish mouth to sit tightly

Appreciate ... that's my concern. I cannot understand why he would have welded them up without them being tight.

Yes, one's a 90 join, the other triangulation at other angles ... but the same rules would apply I thought.

One piece rattle back and forward may be 5mm or more before it was welded up. Another was notched to fit around previous plating, which has since been removed, and so therefore would only have actually contact over, say, 50% of the joint, and the other 50% be filled up with weld.

In the case of the right angled cross brace (a rectangular section to a round tube), first he welded it on top of the frame rails then somehow took it off and re-welded it under the frame rails where it was supposed to be for clearance's sake. I'm pretty sure, again, there was only about 50% contact and, again, the rest is just gap and filled with weld.

I'm having other problems with him following instructions and so I'm starting to think he's just taking the **** and treating me like an idiot. I mean, if you have a choice of a notching another pipe to create tight fit or not a tight fit, why would you chose the latter ... unless it was just to bish-bosh a job and get it out quick? It's not as if either the metal or the time it take to cut is the expensive part of the job.


02-26-2016, 8:09 AM
Pics would help.

02-26-2016, 9:04 AM
Unfortunately, I don't have very good photos of them at present. The frame is still at the shop.

The best I have is below. The width of the gap was about the width of the visible weld (arrowed). I don't have any of other items.

You can see it sinks/sits a little low.


02-26-2016, 10:54 AM
Acceptable gap depends on if it's mig or tig. Mig can fill a larger gap (as seen above), but these are all load / stress bearing surfaces. I sure as shit wouldn't be bridging frame gaps with multiple passes to build mass.

I'm sure there are plenty who would find what you're dealing with to acceptable and never see a problem. Personally, I would want tight fits and if I'm paying I'd either get them or go somewhere else. Anyone worth their salt will tell you weld prep is just as important as laying the bead. Fitment is part of prep.

It sounds like you've gotten some other pretty good indicators that he's not taking this job as seriously as you'd like. I'd move on to someone else.

02-26-2016, 2:52 PM
It sounds like you've gotten some other pretty good indicators that he's not taking this job as seriously as you'd like. I'd move on to someone else.

That's pretty much my position and my feeling. I think he thought I was idiot he could take for a ride with a slap dash job.

I was pretty specific about what I wanted and I get the feeling he's not used to being picked up such details ... as in does not like and it's become a big ego thing for him.

But that then begs the next question ... how much stress on the tube is getting him to cut it all off and then have it re-welded again, and how safe is that?

I see it as a bit of a liability/pay off either way.

This is not the only part I had have to get him to rebuild so far. There were also the swing arm mounts. It's been a pain dealing with personality issues (toys and pram (http://www.usingenglish.com/reference/idioms/throw+your+toys+out+of+the+pram.html) come to mind).


02-26-2016, 7:03 PM
OK for one a good weld does NOT sit on the parent metal. It BECOMES one in the same . the welds in the picture have some back cut ,but do look sound. Yes, there should be minimum gap between pieces ,but I would need to see better pics to determine if its a good joint. Many times you WANT a gap between pieces , such as a slugged and joined tubing seam like you see on a rigid conversion.roll cages and chassis pieces should have the best joint possible ,because they are relying on a fillet weld. I was taught how to weld by a 3rd generation "certified " weldor .I asked him what the strongest weld joint was ,and he said " a butt joint is the strongest .I have only been welding for about 8 years ,so I don't consider myself an expert by any means. Really need mor pics to see what's going on.

02-26-2016, 8:09 PM
I zoomed pic on a good monitor but need a higher resolution photo to tell much.

I suggest bringing a tape measure or something so you can pretend to check dimensions for a possible "bracket change" or something rather than pissing your weldor off. Prices have a way of rising when customers get bothersome.

02-28-2016, 6:01 AM
I can give you some blunt advice. You took your bike to a shop, because you do not feel your welding is up to par. Thats fine we all start somewhere. Your paying this shop to do frame or mechanical modifications. If you dont like something, square up and move on.

I would not give baisleys perf a hard time on their bench test of head flow.
I am paying and have payed them for their knowledge and experience.

I have numerous weld certs and a good experienced background. I can say this, their are alot of factors to a weld and fit. The what if bull shit doesnt cut it, that is seen from common sense. Your weld strength depends on the filler, filler size, filler type, processes, material fit, and conditions. If you want have a educated opinion, go to the library, get information from aws-American Welding Society, your.community college. Also hobart, miller, lincoln welding offer great information.

As far as a butt weld its on the bottom for tensile strength. A full penitration weld with a appropriate gap is far stronger in all aspects.

Good luck

02-28-2016, 7:15 AM
The Internet is a great source of information... sadly, much of it is incorrect.

I was a certified pipe welder for many years. Looking at the pic, I would think the fit was good and the welds sound but it's too difficult to tell from a pic to make a definitive statement either way. Here's a pic of what we call a "coupon" getting ready to be welded in school or for a test. This is how it is done and it will take several passes. The welder will tack it together then pull the spacer wire out. Some guys like a wider gap, some guys like a tighter gap. If the weld is proper it doesn't much matter what the gap was.

When welding a coupon like the one in the pic below, the first pass (the "root") actually welds the pieces together on the inside. This is done by making a "keyhole" first of all. A proper root pass, when viewed from the inside, will look like the bead on the outside.

Sadly, most people do not understand anything at all about pipe welding... but they offer opinions anyways. Pipe welding goes above and beyond structural welding by a large margin. A good pipe welder will pass a structural test with no difficulty at all. Even the best structural welders will not pass a pipe welding test without proper training and lots of practice. I mean no offense to the structural welders here, it's just that pipe welding is a whole different world.


02-28-2016, 7:18 AM
As far as a butt weld its on the bottom for tensile strength. A full penitration weld with a appropriate gap is far stronger in all aspects.

Good luck

This is absolutely correct. 100% correct. There is no debating it.

02-28-2016, 8:34 AM
The butt weld he was referring to was done with a root pass ,then properly finish welded not just two slabs of metal butted up to each other then welded on top. ,I agree pipe welding is a whole different thing. But building chopper frames is not pipe welding. But you already know that.

02-28-2016, 12:10 PM
I'm doing a bare metal up restoration with a few subtle frame modifications, roughly speaking, FXR-ing (mid-controls) and updating an older FLH frame for someone of a short leg. Engine and chassis.

I've been constantly amazed by the lack of knowledge/awareness ... or perhaps integrity ... of just about every so called expert locally. I'll spare you the details. You show them, tell them to do something one way, the logical way ... and they go do it the opposite and illogical way or miss utterly crucial elements, e.g. not drilling out oilways on bushings etc which if I had not had half a brain would have wrecked my engine. I've had to pull them up where their tools were damages, e.g. reamers scoring, and make them speak to their suppliers who confirmed what I knew ... they had to be replaced to do the job properly. And I could go on and on.

With regards to this welding, all I really wanted to know is what gap people would use between two 3 mm thick tubes joining at 90 and 45 angles.

I only know a little about bicycle frame building and there the law is, the tubes just sit inside each other without force or any gaps. Perhaps you cut a little 45 V angle on them.

I'm already into deep doo-doo with this guy after he welded up the swing arm mounts all wrong. Same kind of lack of attention to detail again, e.g. when tubes run straight, why not weld weldments parallel, as original, rather than at an angle ... why not have both sides matching etc. Basically, we had an arrangement and instead of waiting for my drawings and instructions detailing everything if required, he fired off in absolutely another direction meaning that most of the works has had to be re-done. I promise you, it was not that complex and I am not that anal, the wrongness was as obvious as setting it up for one braking system, when I wanted it set up for another.

And, yes, I agree. Now he is a p****ed at himself and is trying to hustle the job out of the way. Frustrated at not being able to fob it off with excuses or delays ... and ramping the bill too, I believe. Or at least, making me pay for his mistakes.

Having cut and shut tube before waiting for parts and instructions, he's also now stuck with a legal responsibility to fix or put back what's been done wrong. It's not something I am going to pay for and walking out the door with my tail between my legs.

I believe he can do the quality and nature of the work. I think he just thought it was a quick job to bish-bosh out and now, having been caught, resents it.

But I don't get it, I mean on one side splate he welds a joint upwards and on the other side, he welds it downwards so visually they don't match. There's a lack of attention to detail that I *really* should not have to detail. Right now, legally, I am stuck with having to give him a chance to resolve it.

But, for me, if it's my bike, and my money, it should be my final decision and if I have the choice of two tubes meeting or two tubes not meeting, or holes being welded up ... I'll take the former.

I just wondered how far I can safely letting him bodge it to try and get it all back again ... or just tell him to strip the lot off.


02-28-2016, 12:29 PM
I think the term for a frame builder that isn't upto is cnut!

Your neck is on the line.

Fock him off and get someone via word of mouth,yeah?

all the best


02-28-2016, 2:10 PM
But, for me, if it's my bike, and my money, it should be my final decision and if I have the choice of two tubes meeting or two tubes not meeting, or holes being welded up ... I'll take the former.

Indeed it is; your bike, your money, and your life. Good luck as you proceed.

02-29-2016, 10:33 AM

You're right ... as you say, "my life". I never even took the logic that far.

This was attempt A and attempt B at doing the swing arm mounts. For me, it's just sloppy and careless to weld one side 'up' and then the other side 'down'. From the photos I have, it does not even look like the brace is inline.

What I don't get is both times I told him to stop straight away and speak to me before cutting and welding, and both times he ignored it and went off and did it his way. For example, I told him I needed a Brembo set up for the rear brake, and he went and did it Twin Cam style.

Why? I just don't get the mentality. Even if he just wants to save himself the hassle ... LISTEN TO THE CUSTOMER!

The mounts, to me, do not look even.


02-29-2016, 3:05 PM
for one that method you are using to tell if the mounts are straight is ludicrous. if your suspect, grow a set and go measure for yourself. then when he finally tells you to fuck off because your crying about which direction he welded your mounts. then go spend 8-20k in tools and learn to do it yourself. now as far as listening to what you want that's a whole different matter. the welds and fabrication look acceptable but if the design is wrong then that's different. it kills me how someone who cannot actually do any welding or fabrication on their own can profess to complain about those who can. why do you continue to complain about this instead of removing the frame and paying someone else to do it?

03-02-2016, 11:26 AM
Because it's about a 4 hour round trip away ... and those are the best pictures he has sent.

Pressumably you do the same kind of sloppy work yourself, and like ripping off customers, and that's why you're being defensive about it?

Had I thought I really had to spec the directions of weld, I would have done so. I made the mistake of taking for granted he cared about the quality of his work and how it looked. "Reasonable care" is the legal definition. I made it clear the look mattered, whether you can see it or not.

Actually, I can MIG. I do a good quality of general or basic fabrication, and I have the kind of attention to detail that makes all the difference on a finished bike. In this case, I was willing to pay as insurance in order to get better as he already had a jig for the specific model.

I am sorry, I just don't have the time to trade insults right now ... but, trust me, I'm great at that too.

What you appear to be saying is, "if you don't have the equipment and the experience, you don't have a right to an opinion about what you're paying for?"

That kind of goes against all those hard won contract or consumer laws we have ...

03-02-2016, 9:10 PM
Not going to argue either. You asked a question and you received several responses. my point was there are varying levels of craftsmanship ,if the direction of welds is important to you that should be made aware at the time you discussed the project. I have quite a bit of experience in fabrication on automobiles from restoration to performance . some customers have different ideas on how they want things done .some aren't interested in details like that ,the factory mig welded these frames ,some by hand some automatically. Older frames were gas welded. None of them were tig welded .so the welds he is doing do not match the frame any way. You are obviously not happy with his work. I still think you should just retrieve your frame and seek another fabricator ,the relationship is just going to deteriorate even further .then there's lawyers and threats and all kinds of drama over a motorcycle project that is supposed to be a fun thing .

03-02-2016, 9:39 PM
Fuck outsourcing, learn what you need to know, buy what you need to buy and fab what you need to fab to do it yourself. I bet you'd be happier!

What you've probably paid for on work you don't like could have bought equipment you can enjoy for many years. Gear pays for itself surprisingly fast and gives you freedom you can't get any other way because it's at hand when you want it. More tools are even better than more motorcycles.

03-03-2016, 2:03 PM
The answer I was looking for was something like "1/16" to 1/8" maximum" (fit-up).

What happened in this case was that we made an agreement that the frame builder was not to start work for one month (his stipulation to which I agreed). I accepted as it gave me time to supply drawings and mark up other parts. Instead, he went off ahead of schedule and without warning, did it all without them, and screwed up the job. No consultation nor warning ... I'm still amazed at the stupidity of it from his point of view. He has nothing in writing.

I formally instructed him to stop ... and he did not. Cutting most of it off and then, I only just found out, doing it again ... again without consultation or reference to the written instructions and drawings which I had then supplied.

First time around, he got 4 out of 3 things completely wrong, e.g. set up for wrong generation of brakes, crossbraces interfering with other elements etc. He then got the second attempt wrong too ... and has yet to resolve the braking issue which essentially makes the frame unusable. I'll show you how uneven the first attempt was.

Legally, I am complete covered because I was clear and specific in writing (stop ... discuss ... agree ... and specific on paper etc), although I would face the hassle of going down that route and, as you might imagine, relationships are a little "tense" at present and not at all simple ... and, yes, you are right. It's taking the shine out of something I take great pleasure from and doing. Like finding out your woman's been raped and not only knowing who did it, but that she's still in there.

He's obviously provoking a situation hoping I'll react. I'm trying to salvage something of value out of the situation ... including my frame and transmission.


03-04-2016, 2:34 PM
Fuck outsourcing, learn what you need to know, buy what you need to buy and fab what you need to fab to do it yourself. I bet you'd be happier!

I can get behind this for the most part...however, I need to get some 41 mm x 43ish mm(?) oilite bushings made for some Barney's fork sliders. I don't own a lathe, I plan to get one but that's someday, somewhere way over there. I'll need to outsource it. For guys getting up to speed with this craft - do what you can to learn as much as you can and make a bunch of mistakes. Hone your craft.

But be practical, but don't risk safety. And don't spend too long banging your head against a wall. Accept your limitations and build a plan to get past them.

Sorry - don't mean to highjack.

03-05-2016, 10:09 AM
Fuck outsourcing, learn what you need to know, buy what you need to buy and fab what you need to fab to do it yourself. I bet you'd be happier!.

Largely, I agree with you and do ... and have often done a better job than paid for "expertise" ... but certainly situations are demand purely financial considerations ("return on investment"), and others are due to time limitations. Time is not something you can buy ... in those circumstances, others people's time is what you buy.

Frame modifications though are not something you want to experiment with and get wrong first time round.

One question please ... this is a early/mid-90s frame. From memory, the welds looked pretty neat and clean, with only a little splatter here and there.

I know the FXRs were all hand done, by that time, and on the FLHs, were they still hand done?

Were they gas or MIG? I remember for sure they didn't have that neat "row of pennies" look really good stick welding dones.

I know MIG can be done well, but would have preferred gas for the look of it ... again I did not get the chance to discuss that before I "got what I was going to get".

Will there be problems in the frame's behavior mixing the two?

His work is pretty uneven ... you can see a big piece of pigeons*t in one place. Bottomline is, good work *should* be even, and things like direction of run considered.

A customer really should not have *needed* to have to spec that.

Thank you.

03-05-2016, 3:53 PM
Interesting MIG thread:


03-06-2016, 8:11 AM
The whole stack of dimes effect from mig welding ,is just a process of how you whip the welder. It has gotten to the point where if consumers don't see a pretty stack of dimes ,it must be a bad weld. That's not the case with might welding. Stacked beads on a mig weld is just a technique ,it doesn't prove anything about its structure. The factory welds on my 2001 sportster look like shit ,but I trust them .my aftermarket chopper frame has some nice looking welds though.but that helps sell frames. I do agree the quality should be consistent .when paying someone to fab your stuff

03-06-2016, 9:11 AM
Can't find a way to send a pm to you so hope the welder isn't keeping watch on here.
An old saying.... "If you tell someone the truth, make them laugh. Otherwise they'll kill you."
Obviously the welder has his back up. Whether the work is right or wrong it's probably a good idea to get his attitude 'improved' if you're going to let him complete the job..
Maybe take a bottle over and say sorry for the pressure.... I know you are trying to do the best you can (dig). Let's try and work together from now on (dig) to try and prevent anymore avoidable issues (dig) with my frame (dig). You have the drawings and know what I'm after. So long as the judges at bike events won't catch weird welding shit and so long as the powertrain fits to carry my ass safely and straight down the road I'm good. Call me when the fuckers done. But hey, please no more zero gravity welding where up or down seems the same, OK?"

Maybe put it in writing in an 'I'm sorry card' or something so he can show it off and brag about it... meanwhile it's right there in back of his head so maybe he'll correct his work.

May sound crazy and chickenshit, but you need be happy and he needs to better listen to customers.

03-06-2016, 10:53 AM
... But hey, please no more zero gravity welding where up or down seems the same, OK?"

I am sure you're right. It's just the temptation to apply the bottle direct to the head, rather than open, it is a little too strong right now.

I guess the rest of you feel much the same about being disrespected or treated as if you were an idiot with a knowingly half-assed job and run around.

Personally, I would not be fussed how the weld was, as long as it was consistent. I know how to make puddles and pennies but I would not say he even hit that mark either.

Unfortunately, I've seen some good welding, e.g. here's a comparable from an old '60s Rickman Matisse frame ... for me, his using a MIG was just more evidence of cheap-ass/half-ass approach. My feeling is he thought he could take a dump on me and is not p****ed at being caught out.


03-06-2016, 10:57 AM
Interesting MIG thread:


There is some *seriously* good welding in that thread. Real masters.

If this guy was on dope when it clamped it up, it sure wasn't to steady his hand. I'm thinking of those old "spider on acid" spider web pictures you see.

03-06-2016, 1:18 PM
That looks like some really good gas welding there. Nice frame. Maybe you should have shown him those pics as a reference to the look and quality you were wanting. I once had a guy bring in a set of hand build aluminum sheet metal valve covers from a really expensive well known shop. He said he wanted to weld some breather tubes into them . He referenced the welds on the covers , and asked if we could replicate them on the breather tubes ,and I said yes. These were the infamous dime stacked aluminum tig welds you see every where that every one loves.he said are you sure ?! As if it was some magical process.I then said if they don't match perfectly I'll buy them from you for what you paid ,400.00 if I remember. When he came to pick them up he said wow!! I didn't think it could be done,how much ? I told him 30.00 and he couldn't believe how cheap I did it for. I could have charged him 100.00 and he would have gladly paid. Some times people need to be specific on how they want things to look. I could have welded them but my style is a tighter bead and he wouldn't have been happy.same quality just different looking.

04-07-2016, 5:04 PM
I'll just say me personally on any notched piece tighter is better (especially for tig) but I always run the notched pipe on the disc grinder to give a little bevel for optimum penetration. Any butt welds I try to use a slug if applicable and bevel the pipe for the strongest joint. However I'm not going to lie when I started welding years ago I filled some gnarly gaps with my mig and they held 100% not saying it was proper but I've done it (if you weld you have to). My advice would be either trust your dude or square up with him and find someone you can.