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View Full Version : Using tubing for frame slugs instead of solid round bar?



nateridesbikes
01-04-2013, 11:50 AM
First things first, I dont have a lathe otherwise Id just turn down some round bar and be done with it.

As far as strength is concerned I think it would be fine to use either DOM tubing or structural steel pipe for the frame slugs. My concern is with fitment. Would the tolerance be good enough to fit one piece of tubing into another? Also, I know people say not to use pipe for building frames and what not but wouldnt it be ok for slugs?

I should also mention that Im not using the slugs to extend any of the existing tubes. Basically using them to strengthen the butt welds.

motorlou
01-04-2013, 12:35 PM
i usually turn slugs down on the lathe as well. most of the time the frame tubings inner diameter is bigger than the tubing's i am using. if they are the same though i have used tubing as slug. i don't feel comfy using anything with a wall less than .120 wall though

Jeffy
01-04-2013, 12:38 PM
I would say yes indeed. Just try to keep the tightest fit you can get, it worked fine in structural fabrication I used to do. Just get a good bevel on both butt ends and allow the weld to attach itself to both pieces as well as the slug, and the obligatory filled dimples and its good.

The slug would only be additional strength abobe and beyond, and layed out to extend the stresses away from the welded joint and further out into the uninfluenced full strength d.o.m.

bobscogin
01-04-2013, 12:40 PM
This will renew the worn out argument about pipe versus structural round tubing, but in my opinion pipe will work fine. A properly prepped and welded butt joint should have strength equal to any section of the tube, and the slug can only add to that. You gonna put rosette welds on either side of the joint?
And no, I'm not advocating making anything structural out of pipe.

Bob

nateridesbikes
01-04-2013, 12:45 PM
thanks fellas


A properly prepped and welded butt joint should have strength equal to any section of the tube, and the slug can only add to that. You gonna put rosette welds on either side of the joint?
Bob


That was my thought as well and yes it will be plug welded

sohcool
01-04-2013, 12:48 PM
This will renew the worn out argument about pipe versus structural round tubing, but in my opinion pipe will work fine. A properly prepped and welded butt joint should have strength equal to any section of the tube, and the slug can only add to that. You gonna put rosette welds on either side of the joint?
And no, I'm not advocating making anything structural out of pipe.

Bob

The argument comes from the misconception that 90% of people have that all pipe is the same. It's not.

There is such a thing as structural pipe. OSHA qualified handrails and stuff are commonly made out of it, along with a shitload of other things.

You wouldn't want to build a frame out of fluid piping or black piping for liquids, but there's no reason why you couldn't use structural pipe for things.

The frame for my shovester project will be utilizing structural piping in a few places because it makes an awesome lug for a slip fit around OD dimensioned tubing.

nateridesbikes
01-04-2013, 1:27 PM
I have another thought. Typically the slug is going to be inside the tube and then welded. What are your thoughts on using a slug on the outside of the tube? For example: Butt weld the peice and then slide another tube/pipe over the top of it and weld that on both ends.

sohcool
01-04-2013, 2:01 PM
I have another thought. Typically the slug is going to be inside the tube and then welded. What are your thoughts on using a slug on the outside of the tube? For example: Butt weld the peice and then slide another tube/pipe over the top of it and weld that on both ends.

Just slug it inside. Given the forces applied there's a reason that slugging is preferred.

***Note: There are places you can buy slugs online if you look around.

MercuryMoto67
01-04-2013, 2:02 PM
In theory, tubing is stronger than solid rod as far as getting the bend started. Tubing has twice the surface tension. (OD & ID) For slugs, your golden with tubing.

Jeffy
01-04-2013, 6:46 PM
And the over is a bad idea. There is a fine line when weldinv where just a little too much heat and the metal immediately at the.edge..of.the.weld will become weakened. If you do the.slide o er the top then you will have to weak spots, one on either end of the piece intended to strengthen. Not cool then you could have a 4" chunk break out of your frame and that just doesnt sound like a fun ride.

ChopEmUp
01-04-2013, 6:53 PM
Heres my opinion. As long as the slug has AT LEAST the same wall diameter as the frame tubing, and there are AT LEAST 2 rossette welds and a good weld on the beveled ends of each frame piece, you're good to go...

willythepirate
01-04-2013, 7:04 PM
2 rossette welds and a good weld on the beveled ends of each frame piece, you're good to go-yes

Tubing has twice the surface tension. (OD & ID)-surface AREA but same idea

Thats proper procedures according to the FAA and if its good enough for an airplane then its good enough for your chop

And yes I am an aircraft mechanic

LinkBelt
01-04-2013, 7:05 PM
Not that my info is here or there, but a slug goes inside the tubing, when you slide another piece of tubing over a joint it's called a sleeve.

Sent from my SCH-R720 using Tapatalk 2

BMG
01-04-2013, 8:05 PM
ive used old sockets for " slugs" before..
a couple of rossette welds and a good weld on the beveled ends, never had a problem..

SamHain
01-04-2013, 10:08 PM
you can't run wiring through solid slugs!

Jeffy
01-04-2013, 10:14 PM
For the win^something so simple and makes such a large impact

nateridesbikes
01-04-2013, 10:23 PM
Thanks again! Tubing it is.


Just slug it inside. Given the forces applied there's a reason that slugging is preferred.

***Note: There are places you can buy slugs online if you look around.

Ive found one place that sells them but they are 15 bucks a pop.


Not that my info is here or there, but a slug goes inside the tubing, when you slide another piece of tubing over a joint it's called a sleeve.

Sent from my SCH-R720 using Tapatalk 2

Ahh I knew slug wasnt the right term but I wasnt sure what to call it.

The work Im doing is on the seat rails of a cb360. The seat rails have been lowered and Im fixing someone elses work on the rear hoop.

Swing arm is also stretched now and Im moving the lower shock mounts.

http://i114.photobucket.com/albums/n278/sbc500/CB360%20re-build/DSC_0031.jpg

sohcool
01-04-2013, 10:37 PM
Ive found one place that sells them but they are 15 bucks a pop.

Not to be a dick, but $15.00? If $15.00 is gonna make or break you you might be in the wrong hobby. ;)

$15.00 is actually a really good deal for slugs.

But as others have said, you could also just use some tube. Or, one better, get tube that's a decent wall that will ALMOST fit, and have it turned down so that it will be a slip fit.

nateridesbikes
01-04-2013, 10:50 PM
Not to be a dick, but $15.00? If $15.00 is gonna make or break you you might be in the wrong hobby. ;)

$15.00 is actually a really good deal for slugs.

But as others have said, you could also just use some tube. Or, one better, get tube that's a decent wall that will ALMOST fit, and have it turned down so that it will be a slip fit.

Maybe it is a good deal for slugs but if I can get 2 feet of tubing for the same price as one slug, thats an even better deal to me.

SamHain
01-04-2013, 11:03 PM
Maybe it is a good deal for slugs but if I can get 2 feet of tubing for the same price as one slug, thats an even better deal to me.

hell you can almost get a stick of tube for that price.

MIKE47
01-05-2013, 7:31 AM
There is already a lot of good info here. But I'll add a few details. I was taught to try to make the slugs 3x the OD in each side. That usually is not doable on bikes as there's not so much length but try for some length. Bevel the ends of the slugs to reduce the risk of a stress riser. If any flex the sharp edge can put stress on the tube. This is way more critical on .035-065 tubing and 4130 is more affected by it but it's good practice. Good fit is nice but when we are talking vehicles that are not leaving the ground (for very long anyway) a few thousandths of wiggle won't hurt anything. If you work with good DOM in .120" wall the tubing telescopes into the size 1/4 larger. As you are working on a Honda you will be turning the slugs to fit no matter what. Honda used seamed tube so you need to clean that up some and they worked in a lot of .083 wall and some other size that doesn't lend it self to standard fitment. Be prepared to be turning or measuring very well for a machinist to do them. $15.00 might sound like a lot but if you figure cost of material and 10-15 minutes lathe time per slug then you'll realize it's very fair. I do them for about the same price to spec. (depending on material cost due to size or how much material I need to remove).

As for sleeves I have done that too. I was taught you cut 30-45 degree on the ends to spread the load on the weld and get more weld area.