Get started making your own parts

[killbucket]

Let's Make Parts From Scratch, 2010



control arm set cut out...

Warning-all pics are 850 x638 for best clarity of what I'm doing here. Sorry if you have to left-click to see them whole...

I need some control arms for a custom project. I drew them in CAD, but these could have been hand-drawn full-size as well. Use what you have. Here, I've printed out my CAD outlines at 100% size. A Traxxas 8-32 rod end becomes part of each of these, I dropped it onto the sheet here for reference. The clear film is a hunk of Contact adhesive shelf paper.



I've covered the black ABS scrap piece that I'm making my parts from with the contact sheet. Do NOT try to use clear or Scotch tape- it won't peel back off easily. It won't, and you'll use TONS of time getting it all off. Stick with the clear shelf paper, or better yet, and paper masking tape, the blue stuff is best. I'm cheap, so this roll here will do just fine.


Here, I've cut out my printed layout, and sprayed the back with good ol' Super90 adhesive.

(High school memories dept: This stuff will hold a 90lb kid off the ground if you spray the back of his jacket with it, and have pre-coated a ready wall. Don't try this yourself)


Pressed into place center-first, your don't get bubbles under it. Center touches first, then let go of the ends. It will drop into place without fighting.

Be sure to cut off all that excess contact around the edges before moving on.


First cuts.
Rules of thumb:
1. Keep the parts in ONE CHUNK as long as possible.
2. Cut away all outside edges first.
3. Then make as many 'detail' cuts as needed while they are still easy to hang onto. We'll see this as we go along...
4. Save final separation of parts until last.

All of this is because larger parts are easier to hold and move around, and everything we need, isn't large...



I've cut away almost everything that isn't a control arm. while everything's still ONE chunk, I start making incisions into the part details.


These are called relief cuts, and they make cutting out these cavities possible.
BE EXTREMELY careful backing out of these short cuts. You don't want to twist the blade with the part while you do this.


All three locations are pre-cut into the bends in the lines.


Now the center slot on three of the arms are cut out. I just used the cutting edges of the blade like a grinder, and nibbled those whole areas out.



See how I cut across to the end of the cut that was previously made?


Repeating this process, you can 'chop out' these bits.


Zip, chop, cut.


Note complete absence of blood and gore. That's good.


More zippity-do-da.


If this happens, shut off the saw...THEN remove the but. Even if you have to do it over and over. Your fingers (....7,8,9,...?!?!?) will thank you.


Again, fine-tuning the shapes, using the blade to 'nibble away' up to the printed lines.


They're starting to emerge as parts...


This is the only 'SPOOKY" cut I had to make, the slot here on the fourth arm.
I had to cut it free of the main chunk to get 'at' this area, so I was left working a small part, up close and personal to a heartless blade.


Now I just have to cut away that area at the 'vee' shape there...


More relief cuts made.


Chop-choppity. See how the final cuts are all that's left here?
Note the spacing on those particular lines.
It's .03 inch, roughly what the saw removes during a cut.
In other words, make TWO cuts with ONE operation were possible.


Resist the temptation to peel 'em right away.
The little lines left on each one show me where to drill the holes for my pivot bolts.
Now how is that big rod-end gonna get fixed into pace?

You have to find my Mega Willy thread for that.

[mrpink]

Awesome post. A lot of good scroll saw tips there, I think I even picked up a few good tips!

Waiting to see more of this...

p!nK

[C*H*U*D]

I really like your posts Killbucket Great pics, great info and as always, safety is #1!!

.

[5150bronco]

Kill,

If I have steel sheet say 22x28 inches and i want to cut shape out, similar to the control arms outer shape......What machine would I use?

[killbucket]

Originally Posted by 5150bronco

Kill,

If I have steel sheet say 22x28 inches and i want to cut shape out, similar to the control arms outer shape......What machine would I use?

A jigsaw with a metal-cutting blade. If the sheet's too floppy, tape it to a thin chunk of plywood, and cut thru both.

[5150bronco]

Originally Posted by killbucket

A jigsaw with a metal-cutting blade. If the sheet's too floppy, tape it to a thin chunk of plywood, and cut thru both.

1/4 thick ply wood? Thanks for the idea. It might be floppy. I could use vices too to secure it.

[killbucket]

Let's Make Parts From Scratch, 2010 continued


Picking up where we left off, I used a scrap of material (with slots that just happened to be the right width) to quickie-up a drilling fixture, with two small bar clamps. Using this setup, a drilled all the a-arms.


At this point, I peeled off the shelf paper and print-outs. If I had used Scotch tape, this step would take HOURS...trust me on this, don't try to use cellophane tapes at all.


I guess I'll show you how the rod-ends get fixed into these here...



First, I glued all the arms to a strip of .060" thick ABS scrap.


then I scored next to each part with a Stanley blade (it's RARE to see use one of these in a proper knife handle. Copy me at your own risk).


And then snapped free, and the other sides done to match.


So we now have a socket where once was a slot.


Grab da rod-ends now...


And a bit of Oatey Black ABS cement into those sockets, and screw in the rod-ends.

What should we make next...

[5150bronco]

looking good! I am trying to make some shock hoops so going to store and getting the stuff you suggested. thanks.

[arcticjeff]

Always love the do it yourself threads.

[killbucket]

http://www.rccrawler.com/forum/showt...=1#post2283884
oodles more pics of this project.

[killbucket]

One of my first M2HB's, Other than a cordless drill, NO power tools:



My fingers ache thinking about these days.

[monkeyracer]

I still don't understand why you notched the end of the piece, just to go back in and fill it with the ABS cement.

BTW I love that oatey ABS cement; I've used in to make a custom computer touchscreen bezel for my car, as well as my custom dodge quad cab and my TQ6 build uses some as well.

I would probably have just drilled and tapped the end, becuase sometimes you can get air bubbles in the oatey cement, and those lead to weak spots.

[killbucket]

The 8-32 studs in the rods ends are nearly as thick as the arms themselves. In the past, I would try to drill and tap a hole, and botch several, to get 'goods'. I would still have to glue a reinforcement plate over each side, or the threads could tear out sideways under stress.

So I thought it out, rather than spend the time ACCURATELY drilling, and tapping holes, I just hacked out the material, and glued the studs into place where I wanted them. Left overnight*, they are good and solid. Left for 2 weeks, they will be solid as the parent material.

*I traded high-tolerance machine work for sleep-time, nice.

[monkeyracer]

Originally Posted by killbucket

The 8-32 studs in the rods ends are nearly as thick as the arms themselves. In the past, I would try to drill and tap a hole, and botch several, to get 'goods'. I would still have to glue a reinforcement plate over each side, or the threads could tear out sideways under stress.

So I thought it out, rather than spend the time ACCURATELY drilling, and tapping holes, I just hacked out the material, and glued the studs into place where I wanted them. Left overnight*, they are good and solid. Left for 2 weeks, they will be solid as the parent material.

*I traded high-tolerance machine work for sleep-time, nice.

It's one way to do it, for sure. I maybe would have added the braces, let it cure then drilled and tapped the holes, but in the end it's a solid piece (unless there are air bubbles)

One thing that's nice about the cement is it makes a chemical bond, so after all the MEK evaporates, the piece is chemically one solid piece (as opposed to two pieces glued together with a mechanical bond).

I usually let parts sit for two days if they need to be strong, but you can start to sand it usually within about 6 hours (depending on how thick you go...)