What he said!

Here I'm drilling the back plate for the spinner. Mejzlik spinner don't come pre drilled. Anyway, I positioned the prop where I wanted it, basicly centered between the little mounting tabs. I made sure my alignment dowel was all the way down and just drilled out the holes one at a time installing a bolt as I went along.
No misalignment here!

Originally Posted by Pittsflyboy

With regards to drilling prop bolt hole. The problem people have with is is because the table on their drill press is not perpendicular to the spindle. Most cheap DP's have a problem with that. To resolve the problem you should indicate the table using a dial indicator and find out where the errors are and correct them. To have a good result you must also have a good drill guide that can not move while drilling. That's why they are taped for a 1/4-20 bolt. I use a piece of 3/4 cabinet grade plywood which has a counterbored hoe in the back side for the 1/4-20 allen bolt, then only drill through the prop about 1/16" into the plywood. there is no reason to drill from both sides, you are just asking for mismatches in the bolt hole pattern. Solid carbide drills are best for wear and rigidity. If clocking is important once you have the proper clocking you can mark the plywood base or use dowel pins to index the prop against to repeat this process everytime.

I do check the level on the table/base but you have given me some good ideas. I am going to try a few things.

Thank You Spats

Originally Posted by The Dirt Doctor

Interesting! I would call the company where you bought the jigs and let them know about it.

So, the DA 170 has 6-mm bolts do they require a 6.2 -mm hole?

Bobby aka TDD

TDD, This is my first 170 so I did not know off hand. I just checked and yes they are 6mm bolts but know I have to look in the trailer to see what size drill bit i am using. The damm trailer is back at work where it's stored. Won't see that until Sunday. But, 6.2 sounds like an obvious size. I know one of my jigs from DA came with a drill bit so not sure what size it is. I have been using a very good set of bits from Snap-on. I have used the bits from the chain (Homedepot etc.) stores and they are terrible. Won't use them anymore.

Got a lot of great ideas on this subjet and can't wait to work with them. I want to get this prop drilling thing perfect.

Thank you

You can not drill a bolt circle perfectly with out some precision equipment and know how. The problem with using your prop washers as a jig is it's aluminum and can wear easily. The drill jigs we can buy are just drilled patterns and not hardend and not that precision. The one I bought from DA had oversized holes because you have to drill the hole oversize to allow a little clearance for the bolt and also to make up for the runout you have in the BC you are drilling. I think your best bet is going to Harbor Freight and get a cheap set of number and letter drills. Determine what size drill actually fits your drill jig. I would then get colbalt drills from a local industrial tool supply or you can get them from MSC, they're a couple of bucks each, very sharp, very hard and accurate. After you drill the first hole you need to pin that hole but a bolt will allow the jig to move so I would use the shank end of another new drill the size you drilled the hole with for the pin. The drill will get hot and expand and can bind in the jig so don't be afraid to use a little water to cool things down while drilling. You will end up with a very accurately drilled prop. make friend with the industrial tool house you can get all those little drills in all kinds of materials and lengths. I use a 12" - 1/16 drill all the time.

Hey Bill how ya been?

I picked up a small but old drill press at a garage sale a few years back. Seems they made em right back in the day LOL. Leveled up the table to the press head itself using a straight new bit and speed square. This is how we calibrate our chops saws at work and it seems to work. Purchased a jig from DA and also use a 3/4 cabinet grade oak. Place the jig on the prop from the back then use a Allen bolt with washer that is recessed in the oak board to hold the jig secure to the prop. Once the first hole is drilled I push a bolt through to make sure it stays aligned. The one thing I found drilling hard wood and also Carbon props, is to take small amounts of material, instead of drilling straight through with constant pressure on the press. This keeps the bit from acc heat and makes for a cleaner hole as it allows the material to shed off the bit by backing up off the pressure. I use a bit from "MAC tools" and is the size of the hole in the DA jig. So far I've drilled at least two dozen props that are very clean with perfect alignment.

Henry Glad you are on the home stretch and can not wait to see ya fly it this season. On the flip side, I've gotten used to checking out your progress each night before bed. gotta say you make it look easy. Awesome build.

One way I want to try is to drill the first hole and then pin it and bolt it together. Then drill the other holes. I notice my jigs have oversize holes as well so frist I am going to mark the holes with the prop washer and see just where the jig lines up.

Spats

Could also use a transfer punch thru the jig. also have used the transfer punch thru the front plate for the prop.

Then we take the prop to the milling machine and drill it slowly i have had a drill bit drift a little , so now i just take a little extra time and have not had a issue,

Bryon

Originally Posted by E260

Could also use a transfer punch thru the jig. also have used the transfer punch thru the front plate for the prop.

Then we take the prop to the milling machine and drill it slowly i have had a drill bit drift a little , so now i just take a little extra time and have not had a issue,

Bryon

Help a novice, What is a transfer punch?

It is a center punch but you buy them in a set and they are sized to the hole you want. The set I have is like 25 pieces that go from 1/16 up to 1/2. They work great.

Originally Posted by cbarnes0061

It is a center punch but you buy them in a set and they are sized to the hole you want. The set I have is like 25 pieces that go from 1/16 up to 1/2. They work great.

Ah ok, I never heard it called that. I don't do much metal work. I just called it a "punch"

Probably a good investment for me to make.

Thanks,

Man I feel like I robbed Henry's awsome build thread.

Yes they look like a sized drill rod and they are flat on the end and there is a liitle point in the center . works great . never have to by a drill guide .

Bryon

Originally Posted by Envelope Pusher

Help a novice, What is a transfer punch?

Transfer punches have their place in the machine shop for many things, but, there is no way you can beat a properly made drill fixture like the one the DA sells. If you read my previous post of a few days ago you will understand that much more is at stake than simply "drilling" the holes. Good machineshop practice goes a long way in the final result. The drill guide must be restrained for best accuracy, that is why it has a 1/4-20 tapped hole in the 10mm boss.

It's amazing how much discussion there is about drilling a prop! But that's good nice to hear everyones differnt ideas.
Ok, now onto the spinner. The mounting holes for Mejzlik spinners don't come pre-drilled either. There are lots of other choices for spinners but I like these because they are so light and I kind of like the shape of them too.
Anyway, the first thing I do is mark the hole location with a fine felt tiped marker on the little rear lip of the back plate, as shown in the first picture. I then position the spinner nicely around the prop so there are equal amounts of clearance on all sides.
Then I mark the hole location onto the spinner cone as shown in the second picture. (sorry for the glare).
Then I just go ahead and drill the hole, (it helps to make a small pilot hole first). As shown in the third picture.
Just keep going until they are all done.

My daughter found this the other day, it has nothing to do with the build thread but I thought it was pretty funny...