I’m amaturish, and have all the cones I need (5), I guess I don’t understand the advantages of pucks. They lock you in to a set number of sizes, (and bike “standards” never change!) while cones are infinitly sizeable. I’m sure the more tight the tolerance, or more production oriented the set up, the more specific sizes will shine, but I think the goal is low-cost, easy entry for the beginner or hobbyist.
Mine are the Chop Source set and I can have the HT, BB, and ST all set in any size.
They’re probably oversized for bicycles as they’re intended for motorcycles first, but if the goal is Bicycle-specific, Versitile, & Low Cost, that model seems a no brainer.
Simple through holes to mount with bolts, all thread, or acme screw.
Depends on your jig and how you set it up. My head tube height is always postitoned from the front axle pivot on my jig. I have a centre single size ‘puck’ and then have puck adapters. I set the height of the headtube standoff by the fixed scale on my jig. As long as the pointer is at the right height I know my head tube is positioned correctly. Cones would not work for this across multiple head tube sizes.
What I was trying to convey is that since this idea was pulled from the <$1000 frame jig thread, how much scope creep before it misses that goal? The potential produces can say. Whatever features can be added that help the budget-minded frame jig builder will be great.
To puck or not to puck?
The advantage of a puck is that it locates a tube at a known offset distance. This is why most fixtures hold onto a headtube with a puck on the bottom (locating) and a cone on top (centering).
I think the consensus is: No pucks on the cones. Pucks can be a separate part.
Final Cone Geometry
The cone geometry is a 5-second change in CAD. The decision simply comes down to the cost-to-utility ratio, which we can get quotes on from PMW to make the final decision.
What is the mounting solution?
We need to converge on the mounting solution. So far the only suggestion I have heard is M8 Clearance. My only concern with the M8 is that not all T-slot profiles can handle an M8 bolt. Most extrusions can handle M6.
Let’s ignore the hardware size for a second and focus on mounting. Do people want a “precision locating feature”?
I’m voting for C - shoulder bolt. If I’m not mistaken, that’s how most of the pro jigs have the direction of the bolt. I think the bolt head needs oriented like option C to accept an argon gas purge fitting. That’s is, if we are still designing a cone to be able to also fit a back purge TIG weld fitting.
Plus, I think I read somewhere that you can buy a hollow M8 bolt that can be used for a TIG purge. I don’t know where you’d buy that type of bolt. Maybe McMaster-Carr? Here’s one I found on Amazon… Cylindrical Hollow Hexagon Socket
EDIT: oh wait. Nevermind. I don’t know what direction the bolt needs to go if someone eventually decides to use a hollow bolt to add back purging capability to their cone. I assumed you’d want the bolt oriented like it is in option C (above), but I’m not actually sure now because I don’t know how the gas line fitting would attach to the bolt.
Attached are photos of my lower head tube puck of an Anvil frame fixture. You will notice the the step on the bottom of the puck holder that locates it to the fixture and two screws that hold it down. The top piece is threaded and turned to the correct size headtube inner diameter. Very solid and accurate.
that’s an interesting design, but that puck holder piece is a lot of material to just act as an intermediary part. i think in an open design the puck should attach directly to the support arm/bracket to reduce the number of parts
I’m just seeing this thread now, but I am happy to sell the cones I already produce for The Creator Frame Fixture and I just made webstore pages for them (linked below.)
By thru-drilling them and using an OD thread to mount them it makes backpurging through the cone massively simpler. The M16 x 2.0 thread does a great job of precision locating the cone. On my surface plate with test indicator I have gotten shocking repeatability when I tighten the cone into position, sweep it for high spot with a test indicator and repeat over and over. Basically no indicator reading on a .0005" test indicator. Your mileage may vary depending on the thread fit you put into the mating component, but I’m sure it will be adequate for building bikes.
