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Old 01-24-2011, 12:43 PM   #121
Beastly Adventurer
Joined: Sep 2008
Location: West Yellowstone, Montana
Oddometer: 1,155
Nice work

All I can say is "if you ever need a job, call, have a small fab shop in paradise"

but our work tends to be repetitious and boring, not near as much fun as building bikes. Have at it, it's fun watching.
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Old 01-30-2011, 12:24 PM   #122
x3300 OP
Joined: Mar 2005
Location: San Jose, CA
Oddometer: 170
Originally Posted by bikecat View Post
Literature on the net makes it sound next to impossible.
Bikecat, everything I post here is genuine and done by my own hand. I try to make it entertaining to read the reports so don't include some details, but nothing is faked nor presented in a misleading way.

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Old 01-30-2011, 12:28 PM   #123
x3300 OP
Joined: Mar 2005
Location: San Jose, CA
Oddometer: 170
Arm Update

As I mentioned in an earlier post, I didn't like the way my lower shock mount turned out. I decided to cut it off and make a new one. I searched around in the McMaster-Carr catalog for a 12mm ID spherical bearing that would match the M12 shock mount bolt and found one with dimensions 12x30x16 that I thought would work. I also found some 17x30x7 oil seals that had the same OD as the bearing that I thought I could use to keep dirt out of the bearing.

Here's how the old mount I cut off compares to my new design. Once I got the arm installed I found I needed to grind down the smaller front gusset to clear the shock's mounting clevis.

I made the bearing holder from a piece of large mild steel round stock I had. I bored the hole out with this setup to give a press fit to the bearing.

Here's the bearing mount tacked to the swingarm. I made it wide enough to accept the bearing and the two seals on each side of the bearing.

I was thinking to add a box section to the bottom of the swingarm to strengthen it. I cut the sections at the bottom of this photo from a length of mild steel rectangular tube.

I needed to grind a curve in the ends where the box intersects the swingarm tube. It is a little difficult to explain, but to lay out the curve I found a short plastic ring the same diameter as the swingarm tube, and with the plastic ring set into the box section I sighted down the ring and marked the intersection with a Sharpie pen, then ground out the curve with a bench grinder. Here are the parts tacked to the swingarm.

The swingarm all welded together. The box section looks big and heavy, but the tube had a thin wall so it doesn't actually add much weight.

Here's a view of the bottom showing the box section. The rear part is just a little too close to the outer final drive mounting nut to get a socket on the nut. I did a little grinding to make room.

After welding the bearing holder and gussets to the swingarm I found that the bearing holder was distorted enough that the bearing could no longer be pressed in. It took a while to get setup, but I mounted the swingarm on a vertical mill and re-bored the bearing hole.

In retrospect, I think a much better way to do the bearing holder would have been to turn the OD of the holder, but not bore the hole, then weld that un-bored holder to the arm and use my arm fixture to get the arm mounted on the mill to drill and bore the hole.

Here's a side view of the arm with the bearing installed which also shows the shortened front bearing mount gusset.

And a view of the bearing mount. The oil seals press in just outside the bearing.

And a view with the arm installed on the bike.

I still want to make a vent for the arm. I just need to drill and tap a hole in the front of the arm somewhere, but I'll wait until I have the fender, exhaust, and whatever else it needs to clear installed before doing that.

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Old 01-30-2011, 01:07 PM   #124
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Location: South France
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SUPERB work thanks for sharing you'r knowlege
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Old 01-30-2011, 02:41 PM   #125
Joined: Nov 2009
Location: Seattle, WA
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Forging ahead, down a false trail.
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Old 01-30-2011, 04:00 PM   #126
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Location: Tropical Far East
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Originally Posted by x3300 View Post
Bikecat, everything I post here is genuine and done by my own hand. I try to make it entertaining to read the reports so don't include some details, but nothing is faked nor presented in a misleading way.

No doubt about that, hence I'm impressed by the way you respoked the wheel so easily! Great stuff.
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Old 01-31-2011, 01:25 AM   #127
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Joined: Jan 2009
Location: Israel
Oddometer: 19
Dear X3300

Can you please elaborate on the wheel lacing?
I am very proficient at building and truing wheels, I used to race bicycles, and used to rebuild motocross wheels in the 80's.
When i had to build my beemer wheels I encountered difficulties, no matter what i did I couldnt decifer the behaviour of the these wheels.
After I think 2 days of frustration I decided to aproach it a a machine - I measured all the spokes to be the same length, and counted turns on the nuts, without any attempt at trueing - and got to within BMW spec for these wheels.
I wonder If you did it differently, and if so, if you please let us hear a little about it (even though it's much less interesting than all the other amazing stuff you do!).

TIA, Miky
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Old 01-31-2011, 11:54 AM   #128
Rapid Dog
bikes, booze, broads...
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Joined: Oct 2003
Location: Strangel Living West of Hell, SoCal
Oddometer: 9,661

...ohhh I'm so jealous of all ye Fab Bastids!...
O.K., I'm in.

Man this has got to handle Baja better the the stocker GS.
'91 R100GSPD Derelict Deux , '81 R100RS Rattlecandy Red/'06 950 ADV Orangeboom/91 R100GSPD Derelict etc.

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Old 02-06-2011, 11:50 AM   #129
x3300 OP
Joined: Mar 2005
Location: San Jose, CA
Oddometer: 170
Originally Posted by mikyheimann View Post
Can you please elaborate on the wheel lacing?
mikyheimann, I don't find anything special about these wheels. I follow standard wheel building techniques and just consider the geometry when making adjustments. I have some detail of building a wheel in my post 'Front Wheel'. There is also a dedicated thread that I have added a few comments to here:
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Old 02-06-2011, 02:27 PM   #130
x3300 OP
Joined: Mar 2005
Location: San Jose, CA
Oddometer: 170
Tube Bender

Rotary draw bending of tubes has little cross section distortion at the bend, and I thought that it would give the appearance I wanted in the subframe and rear luggage racks. Here's a nice diagram I found that shows several tube bending methods.

I decided to make my own bender so that I would then have the capability to make a bender for any size tube or bend radius I might find I need. A minimal design would need a bending die with an integrated clamp die, a pressure die, and a frame.

I found a large block of mild steel at the scrap yard I thought I could use to make a double 1/2" & 3/4" bending die for a 1 1/2" radius. I cut the block down to a square and drilled a hole in the center so I could bolt it to the left over stock I had used to make my lower shock bearing mount. Here's the piece in the lathe almost ready to be turned down.

Once I got the OD turned down I cut grooves of 1/2" and 3/4". I didn't have any full radius cutting tools so I just ground a few left and right hand turning tools to have the proper radius. I had five tools in all to do the grooves, a common center one and left and right radius ones.

Here's the final cutting of the 3/4" groove. After the block was bolted to the mount I drilled a center hole in the bolt so I could support the right side with the center seen in this photo.

Here's the finished bending die with my mount and center drilled bolt.

To simplify the design I decided to weld the clamp die and a handle directly to the bending die. I cut a clamping strap from a thick wall rectangle tube and welded it to the bending die.

I found some 1" square stock to use for the pressure dies. To mill the slots I bought a 1/2" and a 3/4" ball end mill. Here's the milling of the 3/4" die.

Here's a view of the 1/2" die with a section of tube and the cutter.

I had some rectangle stock left over from my swingarm fixture that used for the frame. I cut these slots to allow adjustment of the pressure die position.

Here are all the finished parts ready for assembly.

And the bender in action. I used some c-clamps to clamp it to this sturdy frame. I put some grease on the pressure die to lubricate it. It doesn't take much to bend 1/2" thin wall tube. 3/4" takes considerably more effort.

After doing some test bends I decided to re-work the bending die, clamp and handle. The final version has the handle between the bending die and the frame, the 3/4" grove as the inner groove, and the handle welded to the other side of the clamp die.

Here's a close-up of some bends I could make.


x3300 screwed with this post 02-06-2011 at 02:32 PM Reason: Minor text update.
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Old 02-07-2011, 01:22 AM   #131
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Location: Sunshine coast qld
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That's a nice bender.
A engineer up the road from me made an electric roll bender but he made the die's out of blocks of nylon.
He can bend pollished alloy and stainless without marking the tube.

I thought it was a real nice idea.
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Old 02-12-2011, 11:18 PM   #132
x3300 OP
Joined: Mar 2005
Location: San Jose, CA
Oddometer: 170
Rear Rack

I needed the tube bender to finish up my subframe and make a rear rack. Here's where I left off with just a single fender mount and no rear cross member.

I used my bender to put two equal bends in a piece of 3/4" tube. This photo was from early in the fitting process. The final angles were close to 90 degrees.

Once I got the cross tube fitted I used this piece of aluminum plate to hold it in position for welding. Having the two straight down tubes welded to a cross tube worked out OK, but I think a better solution would be to just use a single long tube and put two bends in it.

I had planned to have a detachable rear rack to save some weight when not in use, but decided simplify my design and have a small rack integral to the subframe. I bent these two 1/2" rails with my bender then ground the ends on a bench grinder so they would mate with the 3/4" subframe tubes.

Here's how they fit onto the subframe. I left some space in front between the rack and the seat to allow access to a seat lock.

To finish the rack I added a front cross member and a center rail.

In my design the fender hangs down below the rear cross tube. I made up this paper template for a small bracket then transfered that to a piece of 16 gauge steel.

I thought the rear cross tube will naturally be used to lift the bike up when it gets stuck in the sand or whatever, so I put a nice friendly radius on the bracket to allow fingers to slide in.

Here's the subframe just about finished except for brackets to mount the side racks, tool tray, seat, etc.

And a mock-up with my old seat pan and a load.

I very happy with my little rack. Its just the right size to carry a small pack and doesn't add much weight.

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Old 02-13-2011, 03:11 AM   #133
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Very Nice
more please...
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Old 02-15-2011, 01:59 PM   #134
The Bavarian Butcher
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Joined: Sep 2009
Location: Atlanta, GA, USA
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This is frickin' awesome.

I am completely envious of your shop tools/skillz.

Fred <|> Need an Airhead Part? .... I May Have It!
'85 BMW R80RT G/Sified <|> '73 BMW R75/5 LWB <|> '94 MZ Silver Star Hack
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Old 02-18-2011, 07:03 PM   #135
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+1 to the comments above

Keep up the good work, and keep posting the updates

The perverse must persevere
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