Enlarging Prop Holes
 

Guys

At times I have the need to enlarge prop mounting holes, normally a prop reamer is sufficient, however I now require the holes to be enlarged from 10mm to 12mm (typical) in the past I have used my drill press using several increasing sizes of drill bits which has been relatively successful. As I said although this has worked, is there a sure fire method that would remove the pucker factor from the procedure, ie is there a jig or process that would ensure that the holes are accurate each and every time?

Thanks and regards.

Peter

RE: Enlarging Prop Holes
 

I have spent 15 years as a machinist and grew up with a heavy mechanical background and following a hole with a drill is a very common and well accepted method of enlarging a hole.

The danger is not in the hole going off center, the danger comes with the type of material being drilled and its thickness, because to do it properly, you can't really hold it in a vise, the piece needs to be free to move - at least for the first few seconds while the drill finds the hole.

The problem is, some materials like plastic can be "Grabby" - likewise with thin material like sheet metal. The drill can auger itself into the part and pull the part (Which is being held down with your hand) up - then the drill can spin the part around and turn your fingers into hamburger.

But with wooden props, I do it all the time (just yesterday in fact). I do it with nylon and composite props too, I'm just a little more careful with them.

And if anyone is wondering about its accuracy, I did a test a few years ago and the hole was less that .0005" (Five - Ten Thousandths of an inch) off from the original hole

RE: Enlarging Prop Holes
 

Thanks for that.

So the way I have been doing it is probably the best, I use a drill press vice ensuring that the drill bit (same size as the original hole) is free to move through the hole, I then tighten it down just sufficiently tight to ensure that it does not move. Then using icremental drill bits, in this case 10.5mm through to 12mm in .5 mm increments I allow the drill bit to find it's centre and slowly drill each succesive size bit until I achieve the desired size.

Good to see that I was on the right track then!

Thanks again,

Peter

RE: Enlarging Prop Holes
 

Yes, that way works great

RE: Enlarging Prop Holes
 

I perfer a prop reamer it's a lot safer just a little more work.

RE: Enlarging Prop Holes
 

Believe it or not, it's actually more accurate to use a drill press. The IDEAL method would be to use a reamer in a drill press, but when reaming a prop by hand you are much more likely to "Wobble" the reamer as you go.

RE: Enlarging Prop Holes
 

I use a stepped reamer in a drill press. I've also used a regular drill bit from time to time. You can also get something like these if you can't find the size of prop reamer you are looking for at a hobby shop: http://www.mcmaster.com/#chucking-reamers/=1l2jau

RE: Enlarging Prop Holes
 

B&B Specialties has some drill bits that have been machined down at the tip. I have been using them for years and they work great.
www.bennettbuilt.com

RE: Enlarging Prop Holes
 

If you want a 12mm reamer, Fox makes one
http://www3.towerhobbies.com/cgi-bin...&I=LXNL18&P=ML
It features a 1/4" pilot reamer to help start an accurate ream. It is then stepped to 10mm and 12mm. It also features steel construction and has four reaming cutters. Includes a slide-on handle.

RE: Enlarging Prop Holes
 

I used to use a step reamer,but sometimes the step would be too big or too small,making the prop not fit snug on the crankshaft.
Being an ASE/GM auto tech,I had a tapered reamer in my toolbox at work that I rarely used.
I brought it home a tried it on some old props to see if it would do the job.I have to taper the front
and back of the prop hole,but I can fit the props perfectly to any size crankshaft.
Here is an example of the reamer I am using.

http://www.outsideoutfitters.com/p-2...ed-reamer.aspx