frame stretch ~my way insert slugs welded inside in

Nov 27, 2013
143
4
18
earth
www.Frankenbikes.com
this may not be the only way or the best way to stretch a frame, but i feel confident in the strength of the end result. Far more confident than simple butt splices

i create insert slugs using tubing with a similar diameter to my work, these are a snug fit inside the work and protrude past the ends of the finished tube ends

this provides structural support, doubles the wall thickness, and provides a heat sink when doing the exterior butt weld allowing better penetration

first i slit the tubing, twice to remove a strip approximately 1/2 inch wide

then i use a rubber mallet to convice the tubing of it's new diameter, gentle - keep it round(ish) and slip it inside the sleeve and ultimately the recieving ends

i drill some holes in the recieving tube, to be welded in, holding the slug in place

then i go back and do the but welds on the exposed work piece
 

Attachments

GearNut

Active Member
Aug 19, 2009
5,104
7
38
San Diego, Kaliforgnia
Wow! It came out looking awesome! I really like the looks of that frame.
That is the way I was taught to do it too, but I have never seen full length slugs used. Usually they extend an inch or so either side of the butt weld area.
Did you grind off the galvanization before welding? For your health, I hope so. The zinc fumes that get created while welding are nasty health hazards.

I look forward to watching the rest of your build!
 
Nov 27, 2013
143
4
18
earth
www.Frankenbikes.com
Thanks, i am happy with it, and am learning a lot from it too

i "came up with" the idea of full lenngth slugs because the matching diameter chrome railing/clothes hanger rod/pole dance pole i found was only .05 wall, but i wanted to keep the overall chrome look, though punctuated with weld bands.

while a health hazard, particularly for prolonged exposure, OSHA standards recommend gring back about one inch of any rust resistant coating (galv, chrome etc.) but if this cannot be done simply using a fan will reduce exposre sufficiently.

check out galvinized metal fume fever:
http://en.wikipedia.org/wiki/Metal_fume_fever
http://www.ehow.com/about_5474409_side-effects-galvanized-steel-welding.html

I usually just use a fan and my total weld time on this was under 30 minutes

i left as much chrome intact as i could...
 

MEASURE TWICE

Well-Known Member
Jul 13, 2010
2,538
757
113
CA
Thanks, i am happy with it, and am learning a lot from it too

i "came up with" the idea of full lenngth slugs because the matching diameter chrome railing/clothes hanger rod/pole dance pole i found was only .05 wall, but i wanted to keep the overall chrome look, though punctuated with weld bands.

while a health hazard, particularly for prolonged exposure, OSHA standards recommend gring back about one inch of any rust resistant coating (galv, chrome etc.) but if this cannot be done simply using a fan will reduce exposre sufficiently.

check out galvinized metal fume fever:
http://en.wikipedia.org/wiki/Metal_fume_fever
http://www.ehow.com/about_5474409_side-effects-galvanized-steel-welding.html

I usually just use a fan and my total weld time on this was under 30 minutes

i left as much chrome intact as i could...
===============

I bought a low profile was mask that fits under my weld helmet. I could use it all the time as it does not make it really hard to breathe. I am with you on ventilation as well.

MT
 

Tinsmith

Well-Known Member
May 15, 2009
1,057
259
83
Maryland
Nicely done! Do make every effort to minimize exposure to the hazardous materials and fumes. I attribute the third eye on the back of my cranium to 25 years of handling lead and soldering fumes, but I survived and life is good playing with these motorized bicycle projects.
Good luck,
Dan
 

MEASURE TWICE

Well-Known Member
Jul 13, 2010
2,538
757
113
CA
I did a frame shrink by cutting off a small slice of the bottom of the head tube for a fork change with less 9mm of threads. The lock nut has a good 5 threads to squish on the lock washer now.

Somehow on the Pink Panther cartoon they just say biggie-wiggy and incy-wincy and its done in a snap. Would be nice if it were that way.

MT
 

2door

Moderator
Staff member
Sep 15, 2008
16,337
154
63
Littleton, Colorado
Look at post #66 here> http://motorbicycling.com/showthread.php?t=13591&page=7 and you'll see your method used to strenghten a frame on a trike build I did several years ago. The trick here was that I had a certain width to work with and had to fill it without disturbing the two ends or the separation between them.

After the stubs were cut to size as well as the filler piece I rosetta welded the stubs in place though two holes drilled in the underside of the frame tubes so the welds would be hidden. I finished it off with a TIG weld around the points where the pieces met.

Like they say, "great minds think alike". Thanks for sharing your ideas.

Tom
 

curtisfox

Well-Known Member
Dec 29, 2008
5,391
2,052
113
minesota
Thats the same way i did a girls fork tube to shorten it the 1" that they are longer then a boys fork. Only i left a 1/8" gap between the tubes for a weld besides the rosett welds...Just Just got to remember to put the bearing race on before welding......Curt
 
Nov 27, 2013
143
4
18
earth
www.Frankenbikes.com
math for slug insert slit

the slugs work by snugly fitting in the existing tubes
in order to do this a slit is made inthe tube I just restimated and re-estimated, and was surprised at how large a slit i needed to make in ordeer tio do this

thinking about another project, i realized that the math for slitting the insert slugs is

((tube wall thickness)*2)*pi [3.14]= (slit width)

.065" * 2 = .13" .13" * 3.14 = .41"

that is: two walls times pi gives the width if the slit


[ i think - does this seem right? i did wind up cutting about 1/2" slits
i wil try this soon...]

circles are amazing