How to enlarge existing hole?

Richard · Jul 6, 2019

I've got this 1/2" plate mounted to back of PTO. I mount my mower to it.

The plate has an approximate 4" hole for the 1000 shaft to poke through and and a (don't know the measurement) 1 1/8" hole for the 540 shaft to poke through. It totally fits around the 540 shaft but it gives me the heebie jeebies that one side of it is too close. (I know that as long as it's not hitting, it's not too close but I'd like it slightly further away)

The 540 shaft is (slightly) but noticeably off center. I'd like to enlarge the hole maybe 1/8" to maybe 3/16"

I currently have bracket removed and in my hands.

I was thinking maybe a stepped drill bit?

Reading up on them, people use them for thin metal, wood.... not seen anything about 1/2" steel so it might not be up to the job.

What's best tool to simply ream out an existing hole a fraction of an inch??

Gordon Gould · Jul 6, 2019

I have done that kind of thing with a hole saw. Find one the size you want. Then take a metal plate, 1/4 to 1/2" say, and make a hole. Then clamp your plate on top of the piece you want to drill out so it acts as a guide for the hole saw. Use a low RPM drill, some cutting oil, and blow out the kerf often if you even have a kerf with just a slight enlargement. I use a rt angle Milwaukee drill or slow drill press. A large 1/2 round file would also work.

gg

Leejohn · Jul 6, 2019

Air die grinder with a barred bit. About a 5 min job.

Diggin It · Jul 6, 2019

I can't really tell what we're talking about from that picture. If this plate can be removed, I'd try a die grinder of some kind. Just grind out the area you need, even if it goes a bit oblong.

You might even be able to do it with a rat tail or half-round file if you have room to work.

AWSubie · Jul 6, 2019

https://images.homedepot-static.com...el-rotary-tool-bits-562-64_400_compressed.jpg
These dremel rotary files work really well even on heavy plate.

oosik · Jul 7, 2019

I have taken a very course round file - chopped it down - chucked it into my Milwaukee 1/2" Hole Hog. Does a reaming job on half inch steel plate real well.

RBLapham · Jul 7, 2019

Buy a reamer of the correct size it will be tapered slightly but will be round. Ream also from the other side will help get rid of much of the taper. I used mine to enlarge some old saw blades to fit my new one. it cut very fast - put in my 1/2 inch drill. They are inexpensive also.

https://www.amazon.com/Woodstock-D4...40&qid=1562496807&s=industrial&sr=1-1-catcorr

TractorGuy · Jul 7, 2019

If I see it right the plate is ridged mounted to the tractor right at the shaft so no chance of flex. If it's not hitting I wouldn't worry about it.

Is there some sort of flex coupler to the PTO pump? That alignment would be critical being that close to the shaft.

Richard · Jul 7, 2019

Sorry late to respond.... where to start...

The plate is currently off and in my hands. It DOES mount rigidly to the tractor, I have no reason to think it might flex.

I had a shaft snap and as it snapped, it must have wobbled a bit (?) At the "4:00" position, there is a hot spot and a SLIGHT deformation where the shaft rotated. (shaft is 100% clear of hole when shaft is intact, the breaking of the shaft caused this)

If the shaft is (I don't know) 1 1/8" wide, this must be 1 5/16's wide. It clears but it's close. (you can tell it was well executed and well measured when I had it made.

I've got a 20 gallon compressor. I didn't think of using that to grind it off!!

I've got a right angle (Milwaukee) drill should that need to come into play.

Time to find a grinder bit!!!

Thank you for the thoughts!

Mendonsy · Jul 7, 2019

1/2" plate will take a bit of grinding. You might want to consider taking it to a local welding shop to have them cut the hole out with a plasma cutter.