How do I drill straight axle holes?

[Jewel]

The way I have drilled my axle holes is to put the car block in a mill and drill it with a number 44 standard bit. I take small pecking bites not pulling too hard on the mills handle so the drill hopefully will not walk off of location.

Maybe this is not the best way. Perhaps using a brad type drill would be better and only drilling half way. What about using a reamer as a final operation that may be stiffer than the standard #44 drill. My basic worry is walking off of location.

Another option may be to use a purchased drill guide. If you do not have access to a mill or drill press a drill guide may be your best option if you are questing for the best construction technique.

Another idea I have heard is to cross drill your cars block using a ¼ inch drill along the centerline of your axle holes. Open the hole up and then tightly back fill the drilled hole with something like Aluminum filled epoxy. Now you have a homogenous material to drill into with your #44 drill. Wood having grain may have some hard spots and it might deflect your drill causing problems with alignment.

I am student of Stan Pope’s alignment ideas, and one component to creating a great car is to get some really straight axle holes, however now that you have an Aluminum Epoxy axle hole will the wax paper shim for final tuning still work? Maybe this is illegal in some races, but would it work?

Is the first step in making a great car, very straight axle holes in the body of the car? If true the car body needs to be stable and robust so that axle hole alignment will not vary over the life of the car. Maybe a strong car body needs to be a design consideration as well. How much wood does that take? Would a symmetrical amount of wood around the axle hole help?

These may be somewhat advanced questions, is there a separation between cub and adult pinewood techniques?

[MaxV]

I don't know exactly how you are using the mill, but many people make the mistake of:

- referencing the right side holes to the left side of the block, and
- referencing the left side holes to the right side of the block.

This only works if the sides of the block are perfectly parallel. Most of the time they are not.

So, the solution is to reference all holes to the bottom of the block. The Pro-Body tool does this.

It can also be done on a drill press/mill if the bottom of the block is clamped to the drill press fence for all drilling operations.

Regarding the bit, I use cobalt stubby bits (this may not be the correct machinist's term). I only extend the bit out far enough for the desired depth. I also drill the hole slowly. All of these factors (stiff bit, short bit, slow drilling) minimizing drill bit deflection.

[Jewel]

I would think that optimum axle hole drilling could be done by holding the body of your car once in a machinist vice and then drilling with a good mill.

Carbide drills are really stiff and they cut aluminum easily. I might think that if there is a tendency to walk off of center while using the pro body tool at the bottom of the hole the carbide would slice through aluminum and make the guide hole egg shaped. I would also think that if there is a tendency for carbide to bend it might bend at the end of its shaft away from the tooling guide.

I would prefer to able to drill both rear wheel holes at the same time by going all the way through the block. The steps in drilling might be as follows.

1. Use a center to mark the spot where the drill is going to go.
2. Use an undersize carbide drill to go all of the way through the car. Does Carbide cut wood very well? Maybe a fresh spade drill that is very sharp would be better?
3. Use a finish reamer to ream the hole all the way through the body. The reamer should be pretty stiff and not going through much material so it should not walk off.
4. Drill both the rear wheel holes and the dominant drive hole in one holding of block.
5. Flip the block over and raise the hole about .100 for the non-drive wheel.
6. Check your work. Use a gage pin on a surface plate to see if both sides of the axle hole are at the same height relative to the bottom of block.

How do you check if the front drive wheel hole is parallel to the rear wheel holes?

With having non-homogenous material i.e. wood is the epoxy solution really that much more attractive to improve your axle straightness? Another idea for making the wood more consistent that I have heard is too soak the axle holes in super glue and then ream the final holes. The goal is to make the wood less likely to deform and give you a good finish final cut and robust long lasting straightness as you work through the LBW Alignment operation as shown by Stan Pope.

[MaxV]

The problem with drilling all the way through the car is that the drill bit is virtually guaranteed to flex, creating a non-straight hole. At the size of a #44 bit, no material will always go straight.

That is why I recommend drilling holes only half way through - much less flexing of the bit, and use the stiffest bit possible (cobalt).

If all drilling is referenced from the bottom of the block, then the left/right holes will be parallel.

Regarding front to back parallel, that will occur with a drill press or body tool as long as the wood block is not twisted.

[terryep]

I found out last night that my pin chuck I use to hold small drill bits in my 13" drill press is off by 1 or 2 degrees! Not happy. I may try to get a hold of one of these 1/8" shank carbide bits at:

http://www.national-tool.com/HTML/circuit-board.html

or similar at

http://www.mcmaster.com/

This should fix it for me. A smaller drill press is not an option.

Terry

[Panzer]

Here is another good source for carbide drill bits
http://www.store.yahoo.com/drillcity/index.html

[ExtremePWD]

Thanks for the source. Cheaper than the one I found for carbides.

[jackie smith]

we first drilled our squared block with the pro body tool w/#44 bit. then reamed out the hole with a slightly larger bit. then filled entire hole with epoxy (working time of about 10 min.). next using an axle that has been properly prepped we cut the head off. axle needs to be straightened! we coated the axle with a little grease and inserted it into the epoxy filled axle hole. then using our combo square we made sure axle was square to the body both ways and let expoxy almost set then gently remove axle.you should have a near perfect axle hole. do this before cutting your design. we only spent about 10mins when it came to alignment time .my son took 1st two years in a row.thanks everyone

[pinecarpro]

Also with a small bit you should be drilling at a faster rate of speed about 3,000 RPM

Pinecar

[Stephen's Dad]

Also with a small bit you should be drilling at a faster rate of speed about 3,000 RPM

I don't doubt this is true....I'm just wondering why. Stephen gets nervous drilling axles (with the Pro Body tool) & so he creeps the bit into the body. So far, the holes have always met in the middle. The result always appears nice & straight. But is it? Without some very small diameter & very long gage pins, I would know how to ever be entirely certain.

[pinecarpro]

I don’t think you would want to drill that fast with a Pro Body Tool. Does the Pro body tool have drilling sleeves to prevent the drill from wearing out the tools holes? I would drill slow with tool and fast with a drill press.

Pinecar

[Pinewood Daddy]

I don’t think you would want to drill that fast with a Pro Body Tool. Does the Pro body tool have drilling sleeves to prevent the drill from wearing out the tools holes? I would drill slow with tool and fast with a drill press.

Pinecar

DerbyWorx has said, in this forum, to not use the Pro-Body tool in a drill press. Any misalignment will wear out the tool quickly. I did that last year. We use a reamer in a pin vise and twist by hand. I had a new and improved Pro-Body tool made at work (made from steel!). You're only removing .009 per side (.067 slot to .086 hole).

[pinecarpro]

I agree I did not mean to run the Pro Body Too in a drill press. If using a drill press then you should be 3,000RPM. With the Pro Body Tool I would use a variable speed hand drill. They make drilling sleeves for this so the drill bit does not wear out the hole in the tool . You drill a larger hole in the Pro Body Tool or the one you had made then press in the sleeve.

Pinecar

[slin]

I'd like to stress the importance of squaring the raw wood block first before doing anything. To those that do not know what I'm saying: the bottom the of block (where the axle slots are) must be skimmed flat. After all, this is the primary reference surface. Second each side of the block needs to be perpendicular to the bottom. That way, the side are assured to be parallel to each other. Otherwise, a bit is likely to walk "down the slope" when it contact the wood and you have almost no chance of parallel axle holes. I'm in the camp of drilling oversize, fill (wood filler in my case), and drill to size. Sand the last 3/8" of the pointed end (of each axle) to remove any ridges that will distort the holes.

I'd use a jointer if available. A good tablesaw will do as well.

[pinecarpro]

Pinewood Daddy,

I do the same thing as Slin and I use a drill press.


Pinecar