SPACELINER PITMASTER SPECIAL
- Thread starter tjwilson
- Start date
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TOP TUBES
Working a little backwards on this build. Usually I have a pretty strong idea of how I want to design the rear dropouts. I'll typically start with the bottom bracket-chain stay-dropout assembly and build any seat stays or cantilevers off of that. This time I'm starting with the head tube-top tube connection, running the top tubes back to an approximate dropout location, then designing the dropouts to meet where the top tubes ended up. Idea being that I'd be able to focus more on the sweep and arch of the top tubes as I extended them verses trying to hit a specific dropout attachment point. Seems to be working so far but it is also slowing things down a bit.
Twin top tubes tacked in place.
Marked and trimmed.
This might be a little hard to see. The tubing I'm using is 1/2" dia. For the sleeving I'm using 3/8" dia .049" wall tube. I hope to run the cables through the tubes eventually, it's going to be tight. To help guide the cabling I beveled the insert ends using a rotary tool. Here's a before/after comparison.
"S" bends to get around the rear tire and fender.
Final curved ends.
Working a little backwards on this build. Usually I have a pretty strong idea of how I want to design the rear dropouts. I'll typically start with the bottom bracket-chain stay-dropout assembly and build any seat stays or cantilevers off of that. This time I'm starting with the head tube-top tube connection, running the top tubes back to an approximate dropout location, then designing the dropouts to meet where the top tubes ended up. Idea being that I'd be able to focus more on the sweep and arch of the top tubes as I extended them verses trying to hit a specific dropout attachment point. Seems to be working so far but it is also slowing things down a bit.
Twin top tubes tacked in place.
Marked and trimmed.
This might be a little hard to see. The tubing I'm using is 1/2" dia. For the sleeving I'm using 3/8" dia .049" wall tube. I hope to run the cables through the tubes eventually, it's going to be tight. To help guide the cabling I beveled the insert ends using a rotary tool. Here's a before/after comparison.
"S" bends to get around the rear tire and fender.
Final curved ends.
DROP OUTS
In addition to adjusting the initial dropout design to meet the top tubes I had to determine exactly how I wanted to hang the twin rear brake calipers. I'm planning on a rear rack so mounting one caliper at the top wasn't a real option. Plus, at the top I felt that it disrupted the flow of the top tube through the dropout too much. Positioning one caliper at the bottom and one at the back seemed to work best while trying to keep the size of the left dropout reasonable.
I'm still not exactly sure how the rear tire and fender are going to fit to the frame. I want to keep everything as tight as possible. In order to give myself flexibility I designed the caliper mount slots to run parallel to the rear axle slot. This way everything can move forward or back as needed and stay in the same relative positions. Once I know for sure the final caliper locations I may trim down the bracket a bit more.
In addition to adjusting the initial dropout design to meet the top tubes I had to determine exactly how I wanted to hang the twin rear brake calipers. I'm planning on a rear rack so mounting one caliper at the top wasn't a real option. Plus, at the top I felt that it disrupted the flow of the top tube through the dropout too much. Positioning one caliper at the bottom and one at the back seemed to work best while trying to keep the size of the left dropout reasonable.
I'm still not exactly sure how the rear tire and fender are going to fit to the frame. I want to keep everything as tight as possible. In order to give myself flexibility I designed the caliper mount slots to run parallel to the rear axle slot. This way everything can move forward or back as needed and stay in the same relative positions. Once I know for sure the final caliper locations I may trim down the bracket a bit more.
DROP OUTS (continued)
The top ears of the dropouts needed a little angle adjustment to match the angle of the top tubes. I used some clamps and square tubing to improvise a metal brake.
These need some additional finessing to close the gaps between the dropout and tubing and, the tubes need to be capped yet. Overall I'm pretty happy with the results. Next up will be working back to the head tube with the twin mid tubes.
The top ears of the dropouts needed a little angle adjustment to match the angle of the top tubes. I used some clamps and square tubing to improvise a metal brake.
These need some additional finessing to close the gaps between the dropout and tubing and, the tubes need to be capped yet. Overall I'm pretty happy with the results. Next up will be working back to the head tube with the twin mid tubes.
MattiThundrrr
Rattus All Terrainus
Fixed it for you.I used ALL THE clamps
So cool to watch your process. I've been dying to see you utilize that frame jig.
Mmmmmm....swoooopy...
MID TUBES
Used a template to locate the mid tubes relative to the head tube and worked my way back.
I mocked up the mid tube main forward section and the pieces that bend around the rear tire. The best place to sleeve the two together ended up right near where the mid tubes get welded to the seat tube.
Had to cut, tack and finish weld these two sections before continuing.
The run between the seat post and drop outs on these top and mid tubes ended up having as many sleeves as an octopus's sweater! Needed two more to kick the mid tubes in to meet the drop outs.
Used a template to locate the mid tubes relative to the head tube and worked my way back.
I mocked up the mid tube main forward section and the pieces that bend around the rear tire. The best place to sleeve the two together ended up right near where the mid tubes get welded to the seat tube.
Had to cut, tack and finish weld these two sections before continuing.
The run between the seat post and drop outs on these top and mid tubes ended up having as many sleeves as an octopus's sweater! Needed two more to kick the mid tubes in to meet the drop outs.
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CHAIN STAYS
I've been using the same "dies" that I used on Shortbow to make the "S" bends for the top and mid tubes and, now for the chain stays. Here's a link to that build with info on how the dies where originally made.
Forget where I saw this but, running a file across the two tubes while they're welded together creates a reference line thats been invaluable when sleeving pieces together.
I printed out a full scale cross section of the chain stay area to help make sure I was clearing the brake disc, tire, fender, and hitting the seat tube.
Fitting the pieces together and tacking in place.
I've been using the same "dies" that I used on Shortbow to make the "S" bends for the top and mid tubes and, now for the chain stays. Here's a link to that build with info on how the dies where originally made.
Forget where I saw this but, running a file across the two tubes while they're welded together creates a reference line thats been invaluable when sleeving pieces together.
I printed out a full scale cross section of the chain stay area to help make sure I was clearing the brake disc, tire, fender, and hitting the seat tube.
Fitting the pieces together and tacking in place.
BOTTOM BRACKET
On this design I have the bottom bracket pushed out in front of the main down tube. I started with a straight tube section tacked in place. Then to reinforce that connection I came up with a second piece that curved upward. After seeing it place I wasn't too sure and I might switch to a couple of small gussets below the straight tube. Jury is still out.
On this design I have the bottom bracket pushed out in front of the main down tube. I started with a straight tube section tacked in place. Then to reinforce that connection I came up with a second piece that curved upward. After seeing it place I wasn't too sure and I might switch to a couple of small gussets below the straight tube. Jury is still out.
MOCK UP 2.0
I made some paper & cardboard templates to be able to see everything that I was thinking of together before getting too far into actual building. This is the general direction I'm headed but I'm sure things will change as I go.
I made some paper & cardboard templates to be able to see everything that I was thinking of together before getting too far into actual building. This is the general direction I'm headed but I'm sure things will change as I go.
holy shnikees.
I didn't see that coming...this will be spectacular!
That’s some jet age coolness! The Spaceliners signature touches are all there. I especially like your use and placement of the rack...I nearly pulled the trigger on one to do something similar. Are you fabbing a tank light or adapting one? It looks great!
You make sweet tool purchases!
Frame is going to turn out awesome for it.
Frame is going to turn out awesome for it.
Thanks for the compliments. Guess I need to check-in more often... closing in on a month to give this reply, yipes!
I'm planning on fabricating the tank. I think I can get the front light bezel done in metal by squeezing and sectioning a piece of tubing. Not confident in my sheet metal capabilities to fab the tank itself out of metal though. I've read of a process that involves creating a male mold from carved foam, covering that in a thin layer of fiberglass and then melting out the foam with acetone. After that the part is split and additional fiberglass for strengthening is added to the inside, the outside is smoothed with body filler. That's the plan anyway.
FRAME WELD-UP
I'm amazed when I see some of the images online of welds that professional welders can produce. True artistry. I think I've finally come to terms with the fact that my welds are never going to be able to even approach that type of quality. I can at least get two pieces of metal to stick together though! Here's a few images of my welding "style". I had decided early on that I would be doing a fare amount of body work because of bending dimples in the tubing. Good thing because these welds will definitely benefit from a bit of grinding and filler.
Broke out the clamps again to locate the "webbing" at the front of the rear dropouts.
A little preliminary weld cleanup on the inside of the dropouts.
Outside view of dropout and webbing.
I'm amazed when I see some of the images online of welds that professional welders can produce. True artistry. I think I've finally come to terms with the fact that my welds are never going to be able to even approach that type of quality. I can at least get two pieces of metal to stick together though! Here's a few images of my welding "style". I had decided early on that I would be doing a fare amount of body work because of bending dimples in the tubing. Good thing because these welds will definitely benefit from a bit of grinding and filler.
Broke out the clamps again to locate the "webbing" at the front of the rear dropouts.
A little preliminary weld cleanup on the inside of the dropouts.
Outside view of dropout and webbing.
Welding is a journey and an art. Not a race. I find it to be quite relaxing after doing it for so many years
Loving the build
Duuuuuuude!!! That thing is siiiiick!!! With all the lines it has, it looks like a high-speed arrow about to break through the sound barrier! With the white cardboard mockups, it makes me think of Mike Finnegan's '61 Cadillac drag car he's working on. It just looks like it should go 200 miles per hour.
