Chassis building on a honeycomb ceramic plate.

[JT Previa]

Bill - I like the dummy guide post idea. In the absence of my favorite machinist, I was thinking of building one up from coaxial brass tubes, alternatively with a 4-40 screw in the middle to also act as a hold down. Speaking of hold downs, I've got some ideas I want to try later this week.

I took the plunge and cut into the ceramic chassis block. CAUTION: I used a facemask, and carefully swept up the debris - I don't know if there are any fibrous materials but no need to take chances. This stuff is soft an cuts readily!

I like to set a guide up with the chassis I am building to confirm I've left enough clearance to axles, support blocks, etc. After establishing centerlines with a finepoint sharpie along a row of existing holes, I marked off a typical slot location. Then I drilled two holes (enlarging existing holes), one at each end of the slot. I then used my largest Dremel cut off wheel to carefully slot mostly between them. After, I used a small dental tip to square up the corners. You're eyes will be swimming looking closely at all those holes :roll:



I stuck some rubber feet on the bottom to keep it from sliding around on the bench. My RetroJig is getting there!

JT

[chappy]

Great job JT.
I especially like the rubber anti skid feet.
Bob

[Retro Racer 44]

Hey, I like it, a RETROJIG!

I always set mine on the silicone cookie sheet that I use as my work surface. That holds it still enough for working.

[bill from nh]

Your slot came out looking great! It almost looks like it was factory-made. Nice job. :D

I have rubber feet on my other building jigs so they don't slide around. I need to add them to my ceramic jig as well. I didn't initially add them in case I used it with my micro-torch.

[JT Previa]

Thanks Bill, the material is very forgiving (I tried a variation on your post idea, see below). Seems like we all enjoy a little bit of silicone...uh, maybe I should rephrase that...!

Stopped at the Depot and picked up some more hardware that was Hecho'd in China, some of it even mislabeled.



Spent a few minutes with my drill press and soon I had ....

The RetroJig model # 44
A Triumph of Engineering!



As you can see, I classed up the joint with some brass and stainless steel hardware and brads as well as some hardwood hold downs.

Now this classic tool needs a storage box as elegant as its construction - and I had just the right old world case!



Salut!

JT


Sent from my iPhone using Tapatalk

[Retro Racer 44]

In its cosy little box, it looks too pretty to use. You'll have get another one for actual building and let this one be a shelf-queen. :lol: :lol: :lol:

[JT Previa]

Dave, copy away, good excuse to eat a few Popsicles.

Retro, it will be a shame to dirty it up, I'll have to build very clinically.!

I'm more apprehensive about dirtying up this little altar:



Precision Jig with custom short wheelbase jig holes CNC!d in !

JT




Sent from my iPhone using Tapatalk

[54to69RFine]

Received my jig in the mail today. Now I only wished I had the nerve to take it to my drill press and make a few holes so that it would look like the one above. For now I will be happy setting the pins to allow me to build a few chassis to go under some BRM bodies in my to-do list. So far everything is going along fine, I was able to set the wheelbase, chassis width, and guide location. This may turn out to be the designated fixture for this project. :banana-dance:

[bill from nh]

JT, your jig boxes put my Tupperware containers to shame! <G> A coating of something such as boiled linseed oil will keep that wooden cigar box looking like new, but it will darken the wood.

[waaytoomuchintothis]

Use gunstock oil. The more you touch it, the more brilliant and deep it gets. Dave, you should see that old Mossberg goose gun I have from the early 70s. That is one gorgeous piece of wood these days.

[JT Previa]

54to69, good for you, starting a building project on your RetroJig!

Bill, I've got my share of Tupperware (Market Basket brand, right!) storing unfinished - I mean pending, projects!

Very ironic to be setting tools up as shelf queens, a story of acquisition over execution!

JT

[Retro Racer 44]

[JT Previa]

Retro,

I like the super-extended axles!

Because I often true my wheels after the chassis is started, I end up calculating my clearances on small scraps of paper at my bench. Final tire diameter, axle diameter, ground clearance, etc. Then I'd be interrupted and couldn't remember...so I pledged to make a form to keep track.

Assuming you are building the chassis flat on the ceramic block (with no shims under it) the basic dimensions you need is to measure from the underside of an axle to the outside of the tire. Then subtract your desired ground clearance. This will equal the height of your axle blocks.

If you want to calculate this dimension, the formula is as follows, with example dimensions:

Tire Diameter. .700
Axle Diameter. - .093

Total. = .607
Divide by 2 = .3035

Subtract
Ground clearance - .0625

Block height. = .241

Alright, now where did I put that soldering iron...

JT

[JT Previa]

Just finished the latest accessory for my Retro Jig:











I used a nice dense piece of bass wood (1/2x1/4" approx) cut into chunks and added some 2-56 pan head screws. Allows adjustment from about .575 actual tire diameter (.245" jig wheel dia plus .040 clearance) up well past 1" dia. Time to put away my menagerie of nuts, washers, brass and wood bits I used to use!


JT


Sent from my iPhone using Tapatalk

[waaytoomuchintothis]

JT, that is brilliant. I'm going to do that very thing today. I can't wait.