Draw-bar hole enlarging?

[georgerkahn]

I hope you can provide me some direction. I have a draw-bar for my tractor's 2" receiver hitch on rear, and it has a 3/4" hole in it, for a ball with 3/4" shank. My challenge is newest to me trailer has a 2 5/16" coupler, so I need to screw on a ball of that size. BUT, all of these size balls come with a one inch shank.

Here's my question: Not knowing the properties of the steel draw-bar is made of, I was thinking on fastening it to vice on my (old Delta) drill press. Put a 3/4" drill in chuck to make sure it is 100% in line. Then replace 3/4" drill with a 1" one, and slowly -- with safety glasses on and a bottle of thread-cutting oil in hand to keep steel wet -- attempt to increase size of hole to one inch.

I have S&D drill from 1/2" up to about 1 1/2" in 1/8" increments -- should I go in smaller steps than directly from the 3/4" to 1"? And, is the steel they use for draw-bars too hard for my attempt using a drill bit?

I have too many tools in my shop to readily count, but I have gotten hurt/wounded from the drill press MORE than any other tool(s)!!! (I was a slow-learner on importance of using vice/clamps) Not wishing an accident -- is another reason I'm posting this.

Am I on the right track? One of the major issues is that to clear backhoe, the receiver hitch is quite short - so if I purchased a new draw-bar with a 1" hole, I'd have to both hacksaw off a few inches from rear as well as drill a new hole for retaining pin.

I'm hoping you may offer direction?

Thanks much in advance!!!
geo

[smokeywolf]

If I were in your shoes, I think I'd find a scrap piece of at least 3/8" thick steel. Put a 3/16" pilot hole in it, then follow with your 1" inch drill. Clamp that scrap with the 1" hole over the hole in your draw-bar to act as a drill bushing for the 1" drill. Go slow and use lots of cutting oil.

NEVER try to hold something in your hands while drilling it. ALWAYS clamp it down.

[Jim K.]

The easy fix would go to NAPA and get a 2 5/16 ball with a 3/4 shank....That is what I did, would take a hardened bit to drill a drawbar.

[JonB_in_Glencoe]

you don't say what the trailer is, but I'd consider replacing the coupler with one for a 2" ball, it the coupler isn't welded on...unless there is a reason why this trailer needs the 2-5/16 coupler?

[country gent]

The big issue will be from 3/4" to 1" is only 1/4" or 1/8" on a side. unless you resharpen the drill with less relief ( more like one sharpened for brass) it is going to want to grab and thread itself into the stock. The rule of thumb is a pilot hole the dia of the web on the drill. a 1" drill is probably around1/4"-3/8". Depending on your drill press a solid stop for the vise to bear against or solidly clamped down is important. Heavy Strap clamps would be better than c-clamps. The Steel is tough and cuts hard but can be cut Run slow with lots of oil and keep it cutting don't let it rub as this may work harden the piece.

[Plate plinker]

I like making things too, but buying a different ball is a lot easier. Or just make a new drawbar and weld a ball on it.

[bearcove]

Clamp it, drill it, use oil. Its just steel.

[bob208]

it is going to take a better drill press then one of the common ones bought at tractor supply. you can not get them to turn slow enough. plus they are not ridged enough to use that big of a bit. tractor draw bars are not hard a little tough maybe but nothing better then 4140.

now if it were me I would set the part up in the mill and open the hole up with a boring bar.

[georgerkahn]

THANKS MUCH to all who have kindly responded!!! The trailer is a Carry-on Brand for hauling the tractor, and coupler is welded on, with a dedicated battery box (for brakes) on a bracket at aft end of it. I had thought re changing coupler, but pretty much ruled that idea out. Any replacement would necessitate both cutting and rewelding.
I think I best like the idea/suggestion of drilling first through scrap steel, and following with a 1" bit. My drill press is a fairly stout Rockwell Delta floor model from the early 1960's, sporting a magnetic switch to control its 1 hp motor, foot pedal feed, and a 14-speed pulley doo-hickey (technical term) on top, which will allow me to really slow it down. Upon my purchase, I upgraded the chuck, too, to a good commercial version which should minimize bit spinning -- most likely, if it grabs, motor will be stalled.
I repressed the notion of the bit grabbing and trying to screw itself in -- which is perhaps (fear?) why I posted this query in the first place.
So, Plan A will be for me to change belts on pulleys to really get the slowest speed, attempting to drill with it well-lubed and clamped well.
If I'm lucky/successful, great. If not, Plan B will be to put a new blade on a hacksaw, and try cutting the tube down in length.
Again, my sincere appreciation -- I reckoned if any seasoned machinists were anywhere -- it'd be this site! I'm hoping that bob208's suggestion that the bar is simply, "a little tough" will prove to be true. Sadly, one of the "facts" of getting older is two really good machinist friends with a shop full of milling machines and lathes have both predeceased me... My lathe is but a tiny Unimat.
geo

[bob208]

in most shops we cut three flats on the drill shanks that way they can not spin. your unimat lathe mite be able to do the job look up boring between centers. if you run into a hard draw bar it will be the first one i have heard of and I have drilled a lot of draw bars and mounts for trailers.

[smokeywolf]

One of the things I used to do to minimize a drill from grabbing on break-through and screwing itself down to the chuck, was to drill half way through, then flip the part over and finish the hole by drilling from the opposite side.

[runfiverun]

the bigger shanks and balls are for weight rating.
they make 2 different diameter shanks for the 2" balls for a reason, they are pretty much the break-over point.

[RU shooter]

Unless you already have those big bits I'd call around and find a shop that has a water jet . It would take all of about 2 min to cut that hole and they would prob do it for about the same price as it would cost to buy a good 1" bit .

[Strtspdlx]

No carbide burrs? I have done it before. It is somewhat time consuming if you don't have good bits.

[Blanket]

If what you are calling a drawbar is a hitch adapter that you slide into a receiver and put a 5/8 pin thru, buy one with a 1" hole and cut down to fit and redrill the 5/8pin hole. If it is the drawbar of a tractor run your drill as slow as possible and clamp the drawbar to the table. It will not grab until you are about to break through the bottom side. With a 1hp drill with a foot pedal you should be fine. Just reduce the feed pressure as you get close to breaking thru. Most draw bars on tractors are made out of a CM steel and are tough, not hard

[jonas302]

No problem at all means you have your drill press and bits no reason to buy anything else I have had to drill holes like that many many times with a cordless drill not as fun as my big mag drill but when repairing stuff you do what you need to do if I drill wasn't close by or didn't I would cut it with a torch

I got curious went downstairs and poked a drill in a hitch to check hardness... Soft as a babys bottom Be safe and you will have no problems

[lightman]

If you have a set of bits that big and a drill press I would not hesitate to flood it with oil and drill it out. Clamp it down and crowd it just enough to make the bit cut. I would probably just use one bit, I don't see the need to drill in steps.

[leadman]

Run the belts on your drill press a little loose so they will slip if the bit sticks. I've done things like this many times and you should not have any problems if you secure the bar so it can't spin around. I would try to have it up against the drill press post.

[elk hunter]

If it were me I'd put it in the drill press line it up and clamp it down and using the slowest possible speed try to open the hole with a regular high speed steel drill bit. If it proves to be too hard I'd go buy a 1" carbide masonry drill bit and use it. Masonry carbide bits will drill through some mighty hard steel if you keep the speed and the chatter down. With carbide you need flood coolant or none at all as you can shock cool carbide and cause it to crack.

[bedbugbilly]

I'd try to find a ball with the 3/4" bolt first but if you have to enlarge the hole in the bar, that might be a tad bit much for your drill press. Do you know anybody with a vertical mill that could clamp the bar and use a 1" mill to go down through the hole?