Home brew 104bcd spider

[hellmansam]

So I was looking at a couple of Shimano cranksets I have in my parts box and I remembered reading something about you can use non Boost cranks on Boost frames in some instances. The cranks and BB fit ok in the Primal frame but chainline is a bit off. The tabs for the middle and outer chainrings are where the chainring should be. Could I make a spider out of a scrap bit of aloominum ? Prolly shouldn’t bother but ended up marking out BCD, inner and outer diameters. No machining gear, just a drill press and jigsaw. I’m planning to mount it via recessed holes (it’s 12mm thick) using the 64mm BCD for the granny ring so it will end up face to face with the 104 BCD tabs.
Just because I like doing stuff like this.

g

 

[moorey]

Felix runs non boost cranks on boost frame without issue. Looked into it beforehand.

 

[moorey]

And he’s (fucking) PF, so couldn’t even use spacers to adjust chain line. Much easier and more practical to play with BB spacers if are threaded.

 

[hellmansam]

My Primal frame is threaded, running no spacers there’s equal clearance to chainstays of about 10mm.
Adding spacers would reduce spline engagement on the LH crank so I’ll need my hand carved spider to move the chainring just the right amount while keeping everything else the same. Drilling the holes went OK so far, time to retire for the evening before I stuff it up

 

[fatboyonabike]

jigsaw vs 12mm plate will be quite the show....kudos to you for giving it a go though!

 

[hellmansam]

I'm gonna help the poor old jigsaw by drilling plenty of holes ! Bosch make suitable blades (rated up to 15mm) and it's a pretty decent jigsaw. Not ideal but I'll give it a crack. I'm really just procrastinating while I'm doing a big shed clean up...and too soft to go for a ride because it's raining

 

[Dales Cannon]

Keep us updated. 100% for having a go.

 

[T-Rex]

I've got a bandsaw and a lathe which would make this exercise a whole lot easier. Want to post it to me?

 

[hellmansam]

Want to post it to me?

Thanks but I’m keen to push on, got some goodies from Total Tools after going for a short ride this morning.
Jigsaw blades for Aluminum up to 30mm thick (I thought 12mm was pushing it ! )Plus some cutting fluid and a new hole saw. All stuff I’ll use for other jobs eventually.
Holesaw going OK, will finish that step off this evening

 

[hifiandmtb]

I like this thread.

 

[fatboyonabike]

jigsaw blades are for 30mm extruded not plate.
go slow and keep the teeth clear of buildup
I love the smell of burning trefolex in the morning!

 

[hifiandmtb]

Bosch website says:

https://www.boschtools.com/ca/en/bo...-metal-t227d-30858-p/#section-productbenefits

Versatile blade for aluminum 3/16 In. to 5/8 In. thick, fiberglass 3/16 In. to 3/4 In. thick, and plastic 3/16 In. to 1-1/4 In. thick

That's up to 15mm...

 

[hellmansam]

Ooops I misread the packet, s'ok because it's 12mm thick plate

 

[Flow-Rider]

Do a dummy run with the Jig saw because sometimes they cut miles out of square from the blade flexing on the thicker materials.

 

[slowmick]

I'm waiting to see the jigsaw clamped to something, work piece on a pivot and hellmansam slowly turning it and squirting on cutting fluid as he surfs rotorburn & youtube.

 

[SummitFever]

If you drill a stack of holes around the circumference like you say the jigsaw will work fine. There will be lots of cleanup but it will work. I wouldn't use Trefolex on alu. Great with steel but for alu metho is the go.

 

[hellmansam]

do you mean Kero rather than metho?

 

[Dales Cannon]

do you mean Kero rather than metho?

Both work well. Metho gives a brighter finish when turning.

 

[SummitFever]

I prefer metho for a variety of reasons. As Dales says. it gives a better surface finish, but its also readily available, requires little post machining cleanup, cools the cutter through evaporation and isn't sticky, so chip clearing is improved. As far as cutting fluids/coolant go, it is also fairly environmentally friendly. For what you're doing, you won't need alot of it. Just use a little brush to apply small amounts as you cut/drill etc. You don't need to flood the workpiece in the stuff. It's big drawback is flammability. So don't use it on anything other than alu or near naked flames/sparks etc.

 

[Dales Cannon]

Summit you spelled drinkability wrong...