Holes for Cat 1 pins

[Eric_Phillips]

I was out in the barn yesterday and took another look at the post driver. I measured the holes this time, they are 3/4". I also thought the side plates were welded together but they are just bolted to the rest of the mounting structure. I am sure the plates are heavier than my bench top drill press but I think I can rig the plates up to use the drill press. A friend of mine says he has some great cutting lube that he had to buy in a 50gal barrel and he is willing to give me some. So I will be going to HF for some twist bits and have at it. If that fails then I am going J.J.'s route and welding the pins on.

 

[porta mill]

I have been readingthis psting. i was wondering if you use a twist bit are you planning on useing a few different size bits to increase the hole size or just try to drillthe 3/4 hole . I am a machineiest by trade and i reccomend increasingthe hole in steps not just go from 5/16 to 3/4.

 

[Runner]

I thought the step drill bits looked kind of hokey when I first saw them. But I bought a couple of cheap ones from HF and have found them to be the best thing since sliced bread for drilling big holes in thick metal.

I've drilled 7/8 holes in 3/8 thick metal with no problem. I did have to drill from opposite sides though, to keep from having a cone-shaped hole.

One caveat: you need to be holding on to the drill real good when using these. They work by brute force, chipping away at the metal and will tend to grab. I made the mistake of trying one with my half inch drill and it about broke my wrist when it grabbed (just before it twisted the shank off the bit...). Anyway, after that, I stayed with the lower-powered drills.

 

[Eric_Phillips]

I have been readingthis psting. i was wondering if you use a twist bit are you planning on useing a few different size bits to increase the hole size or just try to drillthe 3/4 hole . I am a machineiest by trade and i reccomend increasingthe hole in steps not just go from 5/16 to 3/4.

My hole is currently 3/4" and I want to enlarge it to 7/8". The 5/16" reference was a mistake on my part. Should always measure instead of guessing before posting.

 

[studor]

For the 1/8" --step drill

 

[kennyd]

For the 1/8" --step drill

How is a step drill going to work in 1" thick material?

From the OP:

I need to drill some 7/8" holes in 1" thick plate for the lift pins.

 

[kennyd]

Eric,

TSC, Sears, Home Cheapot and Lowe's all carry large drill bits-they are about $20 each.

 

[CurlyDave]

I have had good results on stuff like this by first making a drill bushing.

Get a small piece of scrap 1/2" to 3/4" steel plate and on your drill press drill a 7/8" hole through the plate. Center this as best you can over the hole you want to enlarge and hold it in place with a couple of c-clamps. Use plenty of lube and go slow. The drill bushing will act to center the drill and prevent wandering.

 

[studor]

How is a step drill going to work in 1" thick material?

Uh maybe with a 7/8" step drill? -- just fine unless it is hardened armour plate

 

[J_J]

You could technically drill through a 3/4 hole to up size it to a 7/8 by using a 7/8 step bit, by using a backup piece of metal. I can think of better ways. Those annular carbide cutters would cut through 1 in steel, but you need a firm base. Some one using a plasma torch , or oxy/acetylene with a hole cutting guide could do it in about 15 min.

Easy way is to just weld the pin on.