CNC Talk Tips Tricks and Techniques

[Daytonatim]

You know, I was just thinking while standing in line at the lunch counter.

This is probably just pie in the sky.......but......

If we could get someone, a modeler from this site, to spcecialized in the laser scanning, using the $100 David Scanner I posted.

He could then sent me the data file by email. I could process it and crank out the master on the mill.

Then I could send the master out to a molder, once again someone from this site, to pour it in rubber and make the part in resin ......

There would be no limit on variety of bodies that could be made

How many people would like a 1/8 scale Cuda......or a 1/12 scale custom 1950's pickup...... or a 1/6 scale model T body to go with those 1/6 scale engines that are being produced......... There would be no limit because we could use the 1/24 and 1/25 scale models that are already out there......

........ and then.........after I get out of this insane asylem.......I will name myself king of the world..... -=';

.......Ok
.......Ok
........ I'm back .....back on earth right now.....I think......

[mrhenley]

I have too much stuff going on already, but I am really wound up about this idea.
As I said, as soon as I can afford it, I will be trying the DAVID system out. I am in negotiations right now, with a guy from Israel about buying one of my eBay cars.
However, this will have to wait a bit anyway. I need to get a lot of other stuff done too. But I will give it a shot.

You know, I was just thinking while standing in line at the lunch counter.

This is probably just pie in the sky.......but......

If we could get someone, a modeler from this site, to spcecialized in the laser scanning, using the $100 David Scanner I posted.

He could then sent me the data file by email. I could process it and crank out the master on the mill.

Then I could send the master out to a molder, once again someone from this site, to pour it in rubber and make the part in resin ......

There would be no limit on variety of bodies that could be made

How many people would like a 1/8 scale Cuda......or a 1/12 scale custom 1950's pickup...... or a 1/6 scale model T body to go with those 1/6 scale engines that are being produced......... There would be no limit because we could use the 1/24 and 1/25 scale models that are already out there......

........ and then.........after I get out of this insane asylem.......I will name myself king of the world..... -=';

.......Ok
.......Ok
........ I'm back .....back on earth right now.....I think......

[mrhenley]

There is so much cool stuff in the air that I am really worked up. I have a weird quirk when it comes to casting , etc. I really enjoy developing the masters, making the molds, and casting the parts. But, once that part is done, I lose interest in duplicating a whole bunch of parts. I design jewelry (sp), and I have never had much luck selling it. That's because once I make a new piece, I have had my fun, and don't really want to make 200 more of exactly the same thing.

With Dan handling the casting , I would really enjoy making masters, and having Dan do the casting .
With Don's help, this could be a major great deal for all of us. Keep it coming guys. This is GREAT!

That sounds like a good idea Tim. Let's let it roll around in Dan and Don's heads and see what they think about this. Dan's the one that will be doing all the molding unless he "contracts" that out to another member.

[Don Garrett]

Hey there Tim, let's see if I can give you quick overview on the question you asked about chopping the top on Big Al. Let's start with a sketch, Chopping the top on say a Model A would be as simple as cutting a section out of the top all the way around and dropping it. Easy huh?
However if you are dealing with a bunch of compound curves it get a little more complex....as (hopefully) the first sketch illustrates that proceedure won't work....nothing will line up after material is removed...

[Don Garrett]

The way I would handle it is shown here, I like to cut a rectangle around the rear window opening and remove the whole section......that way I can cut it down to the size I want and re-install it later....if you don't mind a "mail slot" rear window you can leave it in place.....cut the posts and the rear section of the body and remove the desired amount of drop. Next quarter the top....4 pieces.

[Don Garrett]

Line up the posts and the rear sections of the body...you might have to make a few pie cuts in the lower rear sections of the top to get everything close to lined up. Either bond filler strips or "plastic weld" in filler stips to fill in the voids. If you have two bodies to work with you can leave extra material on each section of the quartered top and not need the filler strips. Cut the rear window down and re-install. That's it.
This is just the way that I do it, some folks try spreading and slanting the posts rearward and inward but that usually doesn't turn out well.

[Don Garrett]

Any of you other members have your own special way of chopping a top?

[Daytonatim]

Hey thanks Don. This will help a lot and the pictures really go a long way toward explaining things.

I have been holding off trying the top chop for a while now. I did glue the floorboard, firewall, and some extra bracing in the body to help hold it in place for when I do finally put the dremel tool to the top. But I just have not been able to bring myself to do it yet. But after seeing your sketches I think I will give it a try this weekend.

I'll post some pics in the Quad Al thread this weekend.

Thanks again

[Don Garrett]

I'll keep an eye out for your posts Tim, if you run into trouble STOP, take a deep breath and contact me, I'LL GET YOU THROUGH IT, NO WORRIES. Email me if you're more comfortable that way.
Remember the first cut is always the hardest....I prefer to use an X-ACTO saw for those cuts as it's easier to keep them clean and straight. Whatever works for you.

[hot ford coupe]

I'll second that. The XActo saw really helps keep the cuts straight. It may take some patience to get a nice cut but it's well worth it.

[Don Garrett]

If you get a chance Tim, drop me an email. I'd like to chat with you a bit about the possibility of producing your Allison.

[Daytonatim]

Hey Don

"You've got mail"

[Don Garrett]

Thanks for the heads up Tim. I'll get back with you shortly.

[Daytonatim]

I finally figured out how to get around one of the problems that has been affecting the surface finish of my parts since I started machining last spring.

It seems the Rotozips I use as my cutter are not as precise as say a bridgeport mill. The collets that hold the endmills in place are not perfectly centered on the axis of rotation of the shaft. This causes the bit to have a slight wobble to it while it is cutting. This wobble is magnified as the endmill gets longer and longer. This wobble causes my 1/8 inch endmill, which is 3 inches long, to leave tooling marks in any finish pass I use it for.

I found that if instead of telling the CNC code generating program that my bit is .125 inch in diameter, I lie to it and tell it that it is .165 inch in diam. and that makes the program leave the part .02" too big. I then use a shorter, therefor less wobble, much smaller diameter bit to to my final finis pass and pick up the fine details. That way there is basicly no wobble, because of the shorter bit, therefore minimal tooling marks left in the final finish.

[hot ford coupe]

Great solution, Tim. I have a similar problem when it comes to using some collets on my wood lathe. There's a minor wobble which when you work with wood is no big deal. When you're doing it with styrene and trying to keep things in scale, it'll frustrate you. I try to keep the piece as small as I can.