Main pivot and lower shock mount

Firstly thanks to Rich for turning up the parts for the main pivot/rear tri in his lathe at work, they worked a treat.

Here is the pivot tube that Rich turned down and put the bearing seats into.


These are the plugs that Rich turned down, drilled and threaded, I then silver brazed them in.


And this is where they go, the seat stays and chain stays will attach on to here.

With a little filing I got the hole to the correct size and fit, it was nice and square and came up really well.


Main pivot after filing, sitting square.

Then I mocked up the assembly with the shock and lower shock mount and it all looked sweet.The alinement was within 0.5mm, which is good enough for this first one, it was a little off because of the hole that was bored through the TT for the seat tube being slightly off to one side, but its pretty good with the ST.


Mocked up and looking good.

Looking straightish and squareish!?

I then sanded and cleaned all the areas where the filler was heading, fluxed it and brazed it in position, it was a nice easy join open and square.



These vent holes are going to be filled.

Daryl was hanging out so he took some pics, this one is especially good, the smoke floating around is from the burning bearing seals that I left in the pivot tube!

I love this photo, I played with it in photoshop, I think it looks better in B&W.

During......

I then checked the alinment again (not that I could do much if it was off !), and cleaned up the lower shock mount, fluxed it, and brazed it in to position too.


It was really hard to get the torch into this area and heat the correct parts but got it fiqured out and it came up really well, its also really hard to finish so it will be pretty much "as is" but it looks all good.

Sitting in position, looking sweet as!

On to the next part jigging the rear tri some how, I'm thinking of doing it in wood, I really just need to tack it then will braze it in the stand.I'll keep you posted.Rossco.

Main pivot hole

Well the front tri is in Richards capable hands for the main pivot hole to be bored.
I needed a mill with a full size table and fixture to mount the triangle to and Rich had his fixture at home plus a machine at work to use.
He sent through some pics of it this arvo, and it looks really good.

Apparently the whole thing is pretty straight, with in 1mm! Sweet.



Also hes facing off the 2 tubes that the chain stays and the seat stays braze onto at 114.20mm. And the main pivot tube itself to the right length (112mm) and boring the bearing seats out to 28mm. I don't have a lathe (yet ;-D ) so I have to get someone who has access to one to do the work for me.
Talking about those two tubes, Rich turned and threaded some little inserts at work for me and I silver brazed them in to the tubes last week they came up good to. Its funny working with silver and not brass, I guess that it got right the way through the joint, it flows pretty good so am pretty confident that it did work.
Now I just have to fiqure away to set the rear triangle up to get it tacked?!Will keep you posted, Rossco.

The rest of the front tri, short of the main pivot.

I have been really busy this past week and a half.

I did the two cuts on the seat tube brace, and it took quite a bit of fiddling and filing to get the two mitres equal and tight, but got there, drilled the vent holes, sanded and cleaned the joint, fluxed it up and brazed it in place.
Still more filing this joint took a while to get right.


This photos not the best, but you get the idea.Check the next one down.


This was pretty interesting the tubes where pretty thin and I took a lot of care not to flame them up to hard, and the beads came up good (the photos don't do them justice). Although the seat tube itself took a bit of a battering from the heat of the torch and has gone a little banana shaped, will sort that out next time the torch gets lit, I have to straighten it before the reamer goes down, other wise the cutter will go through the tube wall.

Got some motivation going and took the plunge on the downtube, I cut the mitre on the head tube and it took a lot of filing to get it right, square, centered and tight. Then I cut the end of the down tube for the tube joint at the bottom, this took a little bit of work to get lined up, I had the "eyecrometer" out to get this sorted and it came out pretty good, although I cut it a little long so I had some room to move.
I brazed in the tube to the end and cleaned it up, and it came together pretty square.


Next for the gusset, I cut this the same as the first, out of an old tube that I had lying around. Shaped it and squashed it to fit, then fluxed it and tacked it on.
I did it differently this time round because I didn't feel like I had alot of control of the heat on the gusset last time. So I chose to tack the gusset on the tube, then tack and check the junction, then do the tinning pass and fillet and then come back to the thin gusset, with all the residual heat around it wouldn't take much extra heat to draw the brass into the gusset area.
So next I set the frame up flat on its centre lines and put the down tube in and checked it for alinement, sanded the junction, cleaned it, fluxed it, then put some heavy weight on the tubes, started sweating! and lit the torch!
I was worried that as soon as I started heating the joint, that it would pull and move all over the shop but I put two tacks down, top and bottom. I let it cool and checked it with machinists square and it checked out good! Sweet! So I then proceeded to the park stand and brazed the joint, did the top of the joint first, then onto the bottom, then sides and finally the gusset area. This worked better than the first time so was pretty happy.


Next it was time to make the junction for the bb>square>dt. Got it kinda lined up on the drawing and marked it out with an old bit of tube the same diameter as the bb, then broke the angle grinder out with the cut off wheel and "roughed it " to size.After this a lot of filing was done to get them matching nicely.



On to the brazing after spending a lot of time sanding and cleaning the parts, fluxing then brazing.
The square took a lot of heat to get to temp and I was worried about the bb being pulled by this, it fared ok but not the tube that joins the square and the downtube, its pretty oval now!but its all good and i'll live with it.

So now on to the clean up I got excitied with the torch so now there are a lot of joints to finish off, slowly but surely!
Also have figured out where the lower shock mount is and made the mount itself hand filed and cut, it looks good. It will be the last thing to go on when the whole bike is mostly assembled. It took a bit of working out, and I hope that the angle of the shock is not to steep should be nice and plush though!

Now all thats left on this is to bore the main pivot in and braze it square and straight!?
On the drawing and looking really good.

Catch you soon.

Cut the seat post to length.

I cut my seat tube to length today, also slotted it for the clamp.Nice and tidy.

I cut it with the angle grinder and a 2mm cut off wheel.

I also have some 25mmx25mm square that I cut 2 pieces from, then cut one face off the square on each piece if this makes sense?! ending up with 2 U shaped pieces that I then filed and welded together to form a rectangle.
Its for the extension from the bb shell to the down tube, it will also carry the lower shock mount.I will join it with a cut tube mitred to the end of the down tube and then to the rectangle extension.


Square before.

And after the 2 pieces joined together.

And cleand up rough with the grinder.

And this is where it sits on the bike (a little hand filing to do yet!).

I also cleaned up the mitre on the ht/dt joint, it was pretty rough and misalined so I just have to get the centre lines of the tubes sorted and will get this brazed on.I would like to get the bb/rectangle/tube/dt all working on the drawing first before the torch comes out!Quess I could do the st brace, have to buy 2 more hole saws (28mm- 44mm) before this happens.

TT/seat tube

Punctured the TT yesterday, it took some time setting the notcher up centred and straight for the cut it was still off some but I cut it with a 25mm cutter and filed the rest to fit.


Cutting in the jig, was hard to set up.


From the top.


Another angle.

As I said it was off to one side when I had finished the cut, I can see now how a lathe or mill would be so much easier to do these cuts, having the x/y movement of the table to adjust things.


But it filed up ok, and I got the angle right! So last night proceeded with the braze which also went well it lined up good on the drawing, a little off at the bottom (1mm) but I really didn't want to file any more out, got a really good feel for the brazing, having 2 fillets back to back, found the heat control quite easy, torch on, torch off, leave the rod in the flame and near the puddle to keep it a consistant temp, also controling the puddle with the torch and making sure the fillet makes it to the root of the joint.


I cleaned up the junction with boiling water as it was a little hard to soak, which works a treat!
I will head down now and clean it up.

Over the drawing after the braze, looking good.

A little off here, though only 1mm or so.

Heres the frame sitting on my home made v blocks on the drawing.

This is my tube cutter it works well but I don't trust that it always cuts square and centered, so I check it regularly with an old bit of tube and a machinists square.For home stuff it seems good, its nicely made, but a lathe would be preferable.

Head tube/TT junction/Gusset

Well have completed this junction today, but first things first, Squashed the tt from 44.5mm to 35mm with my high tech 4x2 tube press.




I have a new respect for steel now after doing this, I had to squash it to some where around 15-20mm (gap), before the tube came down to 35mm!
Then put it in my tube nocther and cut the mitre, filed and cleaned it up checked the joint for gaps.And basically it took a little time to get them matched nicely but in the end it came up well.





looking tight!

The braze went well, had a little fun with the heat control on the tt/gusset area.The gusset was pretty thin and heated pretty fast compared to the tube below.

First I cleaned everything spotless, then fluxed the joint, baked the flux on with the torch leaving the top of the tt clean for the gusset after, I then tacked the joint on either side of the tt, checked it over the drawing which was all good then I fluxed the gusset and tt tube where it is going to sit and tacked on the gusset, then heated the whole joint and proceeded to do the tinning pass, then on to the fillet.



just after brazing

Something is up with the torch or my regs as the flame changed during the braze and had to set it the flame twice.I think the regs aren't sensitive enough for the torch, will have to set the pressure on the regs again for the next joint.

Anyways just after I had finished I checked on the drawing again and it was bang on so was pretty happy about this, its now soaking will hopefully get to cleaning it up tomorrow, and post some pics.




Hmmm stoked to see it lining up!

BB/Seat tube joint.

Today, got my bb/seat tube junction done.Was fun and kinda stressful, but cleaned up really well and am very happy with it.




Post braze and soak


Cleaned up and ready for next joint

Got my new hitachi hammer drill in the post a week ago, man its nice, and quick to get the mitres done now.
Had a super brazing session last week, blew through one of those cheap fuller holesaws in about 5 cuts!But have got the bacho ones now which seem better made and cut better also.
So I did about 4-5 joints in quick succession and really got a handle on the technique for building those nice big fillets.
Found a great tip on the frame forum the other day, grind the outside of the holesaw to get rid of the offset teeth that stick outside the diameter of the main body for a cleaner cut, it works really well.
Theres a heap of great info on that site if you need to know what the pro's are doing its all there for everyone to see, really is a great site for trolling info.Have spent alot of time there lately!

Think I need to have more heat in the tinning pass but the fillet turned out really well, still had the internal micro fillet coming up the back side of the joint which was is good to see.
Think I even got it pretty square and straight!!


Hmmm okay gotta head off, but next comes the big tube squash, have to squash the TT from 44.5mm to 35.6 so I can mitre and braze it to the head tube, should be fun!