Making oval holes round.

/ Making oval holes round. #1  

orezok

Super Member
Joined
Jan 30, 2004
Messages
6,138
Location
Mojave Desert, CA
Tractor
Kubota B7800
The ripper shank holders on my tractor have ovaled out due to use. Currently the pins are 1/2" and I want to upsize them to 5/8". The shanks are already 5/8" and show no wear. I tried drilling them, but the drill bit catches.

I considered laying some weld to get them closer to round. A 5/8" tapered reamer would probably do the trick, but that's $50.

Any ideas what would work best.




 

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/ Making oval holes round. #4  
Problem is with the step drill is material thickness. You'll end up using the next step size to finish the current sized hole, they arent really made for metal over maybe 1/4 inch. The steps are only 1/4 or less deep.


To me it looks like the hole is bigger than a 5/8 pin would be as well. I'd do one of two things. Either weld the correct size bushings on both sides of the hole (if possible due to implement hookup) this would be the easiest and only requires a welder

OR

I'd make one thicker bushing and cut the hole big enough to fit the bushing in and weld in the new bushing all together.
 
/ Making oval holes round. #5  
Use metal guide plate to hold drill in place while cutting over sized hole.

Step 1 - Cut a piece of 1/8" thick metal so it fits in area over hole.DSCN0745 no1.jpg

Step 2 - Put small pilot hole in this new piece of metal in location you want new hole.DSCN0745 no2.jpg
(note - You just want a small pilot hole. Don't make hole too big or you will end up with same issue you have today).
Step 3 - Clamp or temporarily weld this new piece of metal in place.
Step 4 - Using pilot hole as guide, drill new over-sized hole going through both the new metal and old metal.
Step 5 - Remove clamp or cut weld to remove temporary metal guide plate.
 
/ Making oval holes round. #6  
[yep.. torch it out for a hd bushing.. drive bushing in.. weld in from both sides.. grind flat.

BT DT easier than reaming or drilling or welding and drilling.

works better than plating a piece on either side tofix the diameter..

QUOTE=puckgrinder85;3129943]To me it looks like the hole is bigger than a 5/8 pin would be as well. I'd do one of two things. Either weld the correct size bushings on both sides of the hole (if possible due to implement hookup) this would be the easiest and only requires a welder

OR

I'd make one thicker bushing and cut the hole big enough to fit the bushing in and weld in the new bushing all together.[/QUOTE]
 
/ Making oval holes round. #7  
The ripper shank holders on my tractor have ovaled out due to use. Currently the pins are 1/2" and I want to upsize them to 5/8". The shanks are already 5/8" and show no wear. I tried drilling them, but the drill bit catches.

I considered laying some weld to get them closer to round. A 5/8" tapered reamer would probably do the trick, but that's $50.

Any ideas what would work best.


I like the 5/8" taper ream idea seeing as the shanks already have 5/8" holes.
my 5/8ths taper ream is roughly a hundred years old so I'm not sure how much grandpa paid for it :I

If it had to be 1/2 inch holes; I would weld plates on both sides with nice clean holes pre drilled in them
 
/ Making oval holes round. #8  
perhaps try this... weld or clamp a plate on the same plane at the brace, then rent a mag drill and use either an end mill or annular cutter to cut the hole out to a larger size, then use some kind of bushing. You could also put a piece of brass behind the hole and fill it in and grind it smooth and start from scratch.
 
/ Making oval holes round. #9  
If I had to use what's on hand - I still use the step drill bits. I would only drill to the 5/8 size that pops in on top. Once correct hole is started , you should be able to use a regular 5/8 bit to finish drilling since the step drill bits are great for "centering the hole". Using a thick plate with predrilled 5/8 hole clamped on before using a regular bit after starting hole with step bit is a good idea.
 
/ Making oval holes round.
  • Thread Starter
#10  
OK, here's my plan thanks to several of you. I'm going to round up the hole first with a step drill. I've ordered a 5/8" bridge reamer to complete the process. Finally, I'm going to weld in some shims per the attached to take the load off the pin. This should result in a permanent fix.
 

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/ Making oval holes round. #11  
OK, here's my plan thanks to several of you. I'm going to round up the hole first with a step drill. I've ordered a 5/8" bridge reamer to complete the process. Finally, I'm going to weld in some shims per the attached to take the load off the pin. This should result in a permanent fix.

I am not saying your plan is not a good one, but I am just asking a question. If the added shims are going to bear the load front and back and keep from egging out the hole, and it looks like they might do just that... then why bother with repairing the existing hole to start with? I know you wanted to go to a 5/8 pin, but if the 1/2 inch pin is just now holding the shank from falling out, and the shank is now in a "cramp" with the shims and cannot move forward or backward... I was just wondering why?.. Not saying not to do it, just wondering...

James K0UA
 
/ Making oval holes round.
  • Thread Starter
#12  
I am not saying your plan is not a good one, but I am just asking a question. If the added shims are going to bear the load front and back and keep from egging out the hole, and it looks like they might do just that... then why bother with repairing the existing hole to start with? I know you wanted to go to a 5/8 pin, but if the 1/2 inch pin is just now holding the shank from falling out, and the shank is now in a "cramp" with the shims and cannot move forward or backward... I was just wondering why?.. Not saying not to do it, just wondering...

James K0UA

Because I'm retired and NEED something to fill the time! ;) ;)

What better than working on my tractor.
 
/ Making oval holes round. #14  
What I generally do is use a 1/2" od pipe inserted into the original hole location. Then fill the gaps with weldment and drill out the pipe (which is round so the drill doesn't buck).
 
/ Making oval holes round. #15  
I am not saying your plan is not a good one, but I am just asking a question. If the added shims are going to bear the load front and back and keep from egging out the hole, and it looks like they might do just that... then why bother with repairing the existing hole to start with? I know you wanted to go to a 5/8 pin, but if the 1/2 inch pin is just now holding the shank from falling out, and the shank is now in a "cramp" with the shims and cannot move forward or backward... I was just wondering why?.. Not saying not to do it, just wondering...

James K0UA

Thanks for asking that question, so I didn't have to! Boy did I like the answer!:thumbsup:
 
/ Making oval holes round. #16  
I would ink it up, take a circle template and scribe your 5/8 hole. Then take a die grinder and a burr or grinding wheel and grind it to a circle again. I'm thinking 5-10 minutes per hole and it will be perfect. You could leave it a little heavy and finish it with the drill bit but I'd probably just finish it with the grinder. Location should be good enough too because its wore the same on both sides. If you don't have a die grinder then use a drill with a grinding wheel in it and finish it with the drill bit.
 

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