[SloRacer]

Hey everyone. I'm looking for some advice. I am in the process of building a custom r/c truck. I need to see if it is possible to replicate this kind of countersinking without bringing the piece to a machine shop.


This is a factory piece. It has the motor mount screw head area flat milled out. It has to be that style because the motor mount screw holes are slots to allow for adjustment.

The material I am using is .125 aluminum sheet. Unfortunately I have no clue what grade, (6061, 7075, etc) I got it from a coworker who's full time job is a machinist. Maybe it's neither, it is really shiny. Probably should ask him..lol Either way, is it something I can do on my own? Only thing I can think of that might work would be a router, but I don't have one.

Thanks in advance. Now off to get lost in one of the 200 forums you guys got here:cheers:

[Algirdas]

You can do by hand, You can give to someone for water cut. Hardened aluminum is used in truck production mostly. Maybe You better take steel sheet.

[Cmailco]

They're counter-slotted to keep the heads of the screws from being sheared off but I don't think it'd be that big an issue on a truck with plenty of ground clearance. Just use pan or socket-head cap screws.

That or ask the machinist coworker for a favor.

[SloRacer]

Thanks for the response. It doesn't have much ground clearance, in the end it should be around 1.5"-2". It's geared more towards having a low center of gravity and being better suited for racing than the original truck layout is. The stock truck has over 4" of ground clearance to put it in perspective. I attached a pic to show what it looks like at the moment. This is still in mock-up, everything is just bolted to the sheet of aluminum. You can see only the cap head screws are sticking out. Main reason I need them countersunk is so they don't get hung up when landing jumps. But yea, shearing is also a concern there. By the way this has all been done with hand tools, a drill, hacksaw and a file. Haven't had to use the hacksaw yet.

[CJCNC]

Am endmill at the very least should be used, but even with a steady hand, I think it might move around too much and ruin the piece. Good luck with the project.. What's the name of the truck? It looks like a traxxas from the first picture..

[SloRacer]

Gotcha, yea I'm pretty sure I'm going to either find a local shop, or ship it out to one to get done.
The first pic at the top there is the underside of an Ofna 1/8 scale buggy, what I am making is a new chassis style for a traxxas t-maxx.
I also need a few bends done as well, so I may just stick with finding a local shop. 1 bend at 7* and 2 or 3 at around 30* Considering the thickness, I know it won't be accurate if I try by hand, and the 7* HAS to be very close if not perfect, so I need to bring it somewhere that has a bending brake or whatever they are called.

[mrcodewiz]

Do you have a drill press? If so, you could lock the piece on the table and just plunge down using a large end mill. It would be circular instead of oval but it would probably work for your purpose.

[CJCNC]

Just out of curiosity, what kind of ofna is it? I have one sitting in the garage that I am doing nothing with its a Ultra LX Comp.. If you want it, PM me and let me know.. It is in pieces because I use screws for other cars and stuff, and I have drilled up the chassis a bit, but let me know

[CJCNC]

Do you have a drill press? If so, you could lock the piece on the table and just plunge down using a large end mill. It would be circular instead of oval but it would probably work for your purpose.

It needs to be slotted to be able to position and align the motor..

[mrcodewiz]

It needs to be slotted to be able to position and align the motor..

But if the end mill is large enough, there would be enough room to accomplish the same task. The dashed circle is representative of the bolt head in this picture.


Edited to add - Depending on how clean it needs to be, you could also plunge with the end mill, reposition the plate, and repeat the plunge to get the oval.

[SloRacer]

CJCNC- I believe thats the same one I have. Or something similar, Ofna has like 5 versions of the same buggy. It's been my donor vehicle. The only parts I would be interested in is the drivetrain.

I don't have a drill press. Yet. That's actually a route I hadn't thought of. I have been looking around for a drill press. I don't need anything fancy, it would only be used for hobby type stuff for now anyway, but would be much nicer to use then drilling and counter sinking all these chassis holes with a cordless drill. I've been eyeing up a few of the sub-$200 ones. Anyone have any recommendations?

Also, how much am I looking at for an endmill bit? I can't imagine it being very cheap. At the rate it's going it might just be cheaper to get it done somewhere. Basicly this is my prototype model, if this new chassis design makes the truck handle like I think it will, I will be making more of them to sell. So I'm not sure if I really want to blow $200+ for a drill press and bit that might only get used a few times. If it works out well, I would invest more money and get a better drill press to produce these.

[mrcodewiz]

Just to see if its going to work for you, you could pick up a 1.2" chinese end mill for $5. You could probably pick up an older drill press off of craigs list for cheap. I did a quick check on my local CL and there are close to 50. Many for < $50.

[SloRacer]

Why do I always forget Craigslist? Good call. I'll check that out.
Is an endmill something I can pick up at Home Depot, or do I gotta find a specialty shop?

[jalessi]

SloRacer,

You might be able do what you want with a inexpensive drill press like the Harbor Freight model for $54.99

http://tinyurl.com/2baussh

I would save up my money for a G0704, if you are going to make R.C. car parts it would be a perfect solution.

http://www.grizzly.com/products/Dril...th-Stand/G0704

Welcome to the Zone,

Jeff...

[mrcodewiz]

You MAY be able to find one at harbor freight if you have a local one but unlikely. I have a Wholesale Tool (www.wttool.com) in my town which is the only place I can find cheapo endmills outside of mail order. Depends where you live I guess.

[wildwestpat]

Hi SloRacer

Yes this sort of counter sinked slot is easy to achieve using hand tools. Obtain a 'counter bore type - counter sink' tool bit or the appropriate size of screw thread or slot. These cutters have a plain pin that locates in the slot - normal use this would be the clearance hole for the screw thread. The shank of the cutter is shaped to provide the required counter sink. Just take cre you do not get sold a plain counter bore tool as these have a plain square end not the angled face you wish to cut. In the abscence of a drill press to regulate the depth of cut just arrange a piece of tube to act as a depth guide. Crimp the tube if it is too lose a fit and adjust the depth in the chuck of the drill hand or electric to suit the depth of cut required. Plunge the cutter in at the midway point then the two ends and then very gently push the work against the rotating cutter. Do take care to hold the part against a fixed rest i.e. bolt if using a drill press so that the work can not rotate if the cutter grabs. This could damage your hands so think hand drill and work held in the bench vice Yes I know this is a bodge but it will work just take care. There are router bits with guides that might be more easily obtained from your local store. Never ever try using a mill cutter or router bit in a drill press unless you have everything bolted down and even then the drill chuck can be pulled out of the machine is it is held in on a simple taper as most are so do not do it!

Hope this helps - BUT DO TAKE CARE - the bodgers moto! Regards Pat

[SloRacer]

jalessi - gorgeous machine indeed, but something like this is all I think I need for now

By the way, I just remembered why I always forget Craigslist, I live in NJ, people around here are not so nice most of the time. Out of 65 results for drill press, at least 45 were unrelated crap, one was a guy selling his house, haha.