Holes for Cat 1 pins

[Eric_Phillips]

I am trying to modify a post driver to attach to my 3 PH. I need to drill some 7/8" holes in 1" thick plate for the lift pins. Where do you guys find 7/8" twist bits to drill these holes or do you use some other method?

 

[studor]

Ahh somebody has to say it -- Harbour Freight!! They have a set of large diameter drills with reduced shanks that go on sale fairly regularly. They also have step drills but I cannot remember if one is actually 7/8 final diameter (i dont think so) so you could not use them to drill 1" material.
regards

 

[Bird]

Lots of places have the bits. Here is a Craftsman 7/8" step bit and here is a Craftsman 7/8" bit with 1/2" shank. Of course, there's no doubt that Harbor Freight will beat Sears price.

 

[t man]

I would use a good quality hole saw.preferably on a drill press on slow speed.Pre drill the pilot,use plenty of oil to keep the bit cool.And clamp it down.Tim

 

[MJPetersen]

I too recommend hole-saws. I read somewhere that anything over 3/4 that is not a blind hole of course, it is better to use a hole saw. THey will be less expensive than a drill bit too.

Mike

 

[GT2]

A hole saw will work, but I have found that if you want a nice tight hole the twist bit is the way to go!
I would think that for a link pin you would want to keep slop to a minumum?

 

[brandoro]

A hole saw would be second choice for me too. It will make the hole but they tend not to be as true as with a twist bit.

 

[scott_vt]

I would use a good quality hole saw.preferably on a drill press on slow speed.Pre drill the pilot,use plenty of oil to keep the bit cool.And clamp it down.Tim

Good Mornin Tim,
I agree providing the OP doesnt have a drill press. If he does not Lennox hole saws are my favorite !

A hole saw will work, but I have found that if you want a nice tight hole the twist bit is the way to go!
I would think that for a link pin you would want to keep slop to a minumum?

Good Mornin GT2,
As I said above, the twist bit with a sturdy drill press will give the best results. But if using a large hand drill, I favor the holesaw. You may still get a sloppy hole using a twist bit of that size if drilling by hand. Of course, if you have all the toys you could hand drill 1/32 under and ream it for a great fit !

 

[kcprecision]

Eric if you can get the plate off use a drill press or mill at a slow speed and a Silver&Demming drill.

If you already have a large hole a hole saw will be a problem unless you have a plug to fit the hole in the plate and that will keep the hole saw centered.

If you can not get the plated off and onto the drill/mill use the S&D drill with a good hand drill. Watch your self as that drill can/will hang up and twist out of your hands.

I have never tried the step drill in any thing heaver that sheet metal but I don't really think it would work for what you are talking about. The step drill is more for sheet metal, like electrical boxes.

 

[Eric_Phillips]

Thanks for the help. I am needing to enlarge a 5/16" hole to 7/8" so the hole saw would pose some problems. Also there is no way to get the plates off and onto my drill press so I will need to go slow with a hand held. I will keep an eye on HF to see if they go on sale soon.