View Full Version : reaming an oval hole?

09-10-2003, 02:44 AM
to clarify, i dont want to MAKE an oval
hole, but i need to get an oval hole
round again.

i have a 25mm pin going through a 40mm
plate of cast steel and they no longer
fit snugly together. (this is on a tractor,
all the slop in this hinge/pin makes for
a bumpy ride)

the hole is now 25mm x 27mm (oval)
and i want to cut it to 27mm and make
a new pin.

2mm out of round seems like alot to me
and was hoping for suggestions to cut it

hesitant about putting a reamer in there..
and drilling might be difficult.. how do i hold the center?

if i flame cut the hole out, and install a bushing .. will i get it in the right place?



09-10-2003, 03:03 AM
How about making a plug with a pilot hole in the center. Bond it in the oval hole with JB weld or similar material. After it sets up, use the pilot hole to guide the drill as you make the hole the size you need.

You might also use the same approach to ream the hole, but the pilot hole would be larger. Grind a step on the 27mm reamer to fit the pilot hole in the plug.

09-10-2003, 03:55 AM
I wonder if you could temporarily clamp a piece with a round hole over the oval hole, to guide a larger drill bit. I'd be tempted to drill a considerably larger hole than you need, to lessen the chance of the bit digging in and becoming damaged, then make a bushing with the proper hole in it, and press in. Conversely, install the bushing, then drill or ream it to size. I'd want to have a decent wall thickness to the bushing, another reason to drill considerably larger hole beforehand.

09-10-2003, 10:59 AM
I would make an oversize bushing and bolt it to a piece of steel plate that would allow you to position the bushing correctly after you torch the hole out to a clearance. Position the bushing in the flame cut hole so the center is located by some external feature and clamp the plate and then weld the bushing in place.

09-10-2003, 11:00 AM
Another possibility is to build up the hole with brazing around the edges and then drill it to size.

09-10-2003, 06:26 PM
Most pins used on tractors are of common sizes so they can be replaced. going to non standard sizes results in problems later on. Consider Cass and Evans suggestions before modifying.

I prefer to make a bushing, weld it in place and stay with the pins that the tractor came with. It would help to know what part is held by the sloppy pin, but I usually just use temporary wedges, small bolts, tack welds to hold the bushing until I am sure the alignment is "good enough". Make, what ever you use to temporarily hold the bushing, it easy to relocate the bushing. Only when you are sure the pins are in alignment do you weld solid. I have (when i needed two bushing in alignment) put a length of pipe or a long bolt from distant hole to distant hole, tack weld, slip a bushing over the pipe and weld in place. The intent is to keep the bores aligned.

L Webb
09-10-2003, 10:18 PM
If you wish to get that hole that is ovaled out to 27MM anywhere near round, it will need to be reamed larger than 27MM.

It's kinda like when people want me to make them a 6" diameter circle blank out of 6" wide material. It's not gonna happen. You'll have two clipped edges.


09-10-2003, 10:46 PM
You can machine a 25mm plug of copper and build the metal up with a stick or mig if you want to do a quick repair. The welded side with be harder and should last much longer than the old metal did.

Other wise either core drill the hole larger or use a holesaw or O/A or plasma torch to make it big enough for a new bushing. Turn a bushing and weld it in. You should cover the bore while welding as you do not want any spatter in the bore if you intend to ream it.

09-10-2003, 11:52 PM
Is this one of those front axle pivots?Is it the axle or the housing or both?If its both weld or braze up with brass and bore that sucker out in the lathe or mill,unless this is a big tractor,but it being 27mm it ain't that big,the casting and the axle I have set up on the lathe carrage and bored with a boring bar held between centers,this is the best way if you want it to last,by line boring you can get the right size hole,with the right tolerence,and it will fit tight,but still go in easy.It has to fit with tight tolerences because if it don't anything you put in there will pound out in short order,like Thrud says your dealer or an aftermarket dealer can supply you with a correct bushing for your app,good luck.