Tap/thread sizes

[BTackett]

I am looking to drill/tap some M12 bolt holes on the hub of my Mits and wondering if I were going to drill/tap for a 1/2" bolt what size drill bit to use? Reason I am drilling is 4 of the 6 are already crossed. looks like someone tried already to use a standard bolt on Metric threads.

Also, what size to drill/tap to 5/8" bolt?
I found an old chart but it only shows up to 3/8 size.




thanks,

Bill

 

[Grand_Pooba]

I don't think you will be able to use the 1/2 because the tap drill is smaller than 12mm. The tap drill for a 5/8-11 is a 17/32" (.5312). A 9/16-18 (.515 tap drill) would work too but it's a bit of an odd ball size. Hope that helps
Steve

 

[bjcsc]

Here's a chart...

 

[Mundy]

Just a suggestion, If the whole tractor is metric I would keep it that way.

If you change some to standard yes you solve the problem today, but if in the future you or another owner have to replace those bolts for some reason or even just disassemble reassemble it complicates things when some are standard and some are metric.

 

[tlbuser]

and another http://www.imperialinc.com/pdf/I_DrillSizeDecimalEquivalent&TapDrillChart.pdf

I have one of these laminated and stuck to the wall next to the drill press

 

[BTackett]

tlbuser, I now have one of those laminated on my wall! thanks

I normally would not change std to metric but apparently the previous owner decided to do that with the left wheel and then used smaller longer bolts on the right side with washers/nuts on the back side. Not good. So , If I re-thread the right side back to metric and the left side is larger than M12 (5/8") then I would have std/metric rear wheel bolts. I just want to make both sides the same regardless.

thanks for the replies.

Bill

 

[Mundy]

That makes sense. You are correcting the problem I was thinking you were going to create. All lug nuts the same is all the same wheather metric or standard.

Good luck

 

[Jw5875]

Take one of the un-damaged bolts with you to a automotive store.

match it to a "Heli-coil" kit. A little expensive but it will be a professional / original repair. Also buy new bolts along with the kit.

Thread Repair Kits - HeliCoil Threaded inserts for stripped threads, thread repair, stripped sparkplugs



JW 5875

 

[Grand_Pooba]

Helicoils are good idea if you want to get back to the original bolt size (M12) but you'll have to drill and tap the holes to the lager size. I think it's M16 for the M12 helicoil so make sure you've got the right drill/tap on hand.

 

[nate_m]

A good rule to remember for Metric Bolts:

Subtract the pitch from the diameter to get drill size.

For example, the appropriate drill for an M6 x 1.0 would be 5.0mm.

Of course, most of us don't have metric drill bits lying around, so you still need the chart next to the drill press to find the equivalent Americaneze size drill bit...