looking for recommendation on how to drill a 1" deep 5/16" diameter hole in the end of a steel 5/8" bolt. it is crucial that the hole be centered and parallel to the bolt axis. i have a small craftsman drill press, plenty of drill sizes, and a starret auto punch.
the best idea i can think of is to bolt the 5/8" bolt on to the drill press table and hope the press table is perpendicular to the chuck axis. got no clue how to find the bolt center so i can punch it.
If you want it done right, find a friend with a lathe. This will only take a second. I'd do it for a cold one.
Karl
clamp a piece large plate to the drill table
about one inch thick would be fine
drill and tap it for the bolt use a undersize tap drill and a real sharp tap might even hone the tap a few thou under size for a tight fit on the bolt
thread the bolt into the hole from under the table use a nut to lock the bolt in place
drill your hole
will be as centered as practical on that type of machine
be sure to use a good sharp center drill to start both holes
good luck
snipped-for-privacy@yahoo.com (Carlos Valor)
with regard to drilling an axial hole in a bolt end
You can find the bolt center with a combination square's center head. File the bolt end flat, then mark it with magic marker before using a scribe and center head to make crossed lines to pinpoint the center. Punch (the bolt held vertically in a bench vise), with a prick punch, then punch again with a center punch.
If you don't have a center head, go to a place that sells them with the marked bolt and scribe in hand, and do it there. ;)
At the drill press: get a piece of hardwood (2by2by8--or such, whatever's right for the length of your bolt) that you clamp to the table, in the center so that the drill will clear the hole in the middle of the table. Drill the wood with a
5/8 drill (or just under if you have it--19/32). From underneath the table, insert (screw) the bolt up into the hole in the hardwood, and (from the top) run a nut on the bolt down to the top of the wood. Washers on both ends would help. Use spacers if there's not enough thread on the bolt (or thicker wood). Crank the nut down firmly onto the wood. Change the 5/8 drill bit (without moving a thing in your setup) to first a center drill, or something small enough to be able to find the center-punched 60 deg indent you made in the bolt end. Then change that drill out for a 5/16 drill (again, without moving a thing in the setup). Go slow; use cutting oil on the bit. Frank Morrison
The OP didn't say *how* centered and parallel it had to be, or for that matter the length of the bolt and it's threadrd length. One man's idea of "crucial" centering may be different than another's.
He might be able to use your idea but beat the cost of buying a tap and tap drill if he doesen't have them by just drilling a 1/2" hole through that plate and securing the bolt with a nut on top, or one on top and one on the bottom, depending on the bolt's thread length.
Heck, he might even beat the cost of a thick metal plate if he doesn't have any by using a thick hardwood board and some washers under the nut(s).
HTH,
Jeff
yep , several ways to skin that cat
just depends on how nice a pelt you want
On Sat, 11 Sep 2004 18:40:30 -0700, Carlos Valor wrote (in message ):
Put a long drill bit or piece of rod known to be straight in the chuck and use a square to check for perpendicular. Most drill presses have adjustable tables.
Here's a trick that I've used with some success, put the bolt in the drill chuck ! But first you need to get a drill bit clamped very close to perpendicular. I put the bit upside down in the drill chuck, leaving the shank exposed. Then I raise the table up so that I can tighten a vise on the bit (using a spacer as needed). With the drill secure in the vise, loosen the drill chuck and lower the table with the drill bit. THEN put the bolt in the drill chuck. If the end of the bolt is not close to flat, then work it over with a file. Then you have some hope of getting the drill started in the center. Spin up the drill, and carefully feed the bolt down onto the drill, trying to find the center. My experience is that with some practice you can get close, and it's hard to get the bit stared too far off center as it gets thown aside !
One additional benefit of this method is that chips fall down out of the hole when cutting brass etc.
I'd not wager much that one can get the hole within 20 thou of center every time, but it should be pretty parallel, and it's a method you can try with your drill press.
Good luck,
Dave, from Saskatoon where someone forgot to send summer this year, brrrrr :(
You've been given a number of different ways to perform this task. The most difficult part however is still up to you:
You need to decide on a tolerance for your piece. How accurately does the hole need to be placed in the end, and how much deviation from the axis is permitted?
The answers to those two questions cannot use any of the terms:
Dead Nuts On Absolute Perfect etc.
The answer will be something like, I need the hole to be in the center of the bolt within +/- 0.003 inch, and I need the other end of the hole to be within 0.001 inch of the location of the hole's top.
Remember that a) you will have a tough time indicating to the threads on a faster, so unless there is an unthreaded portion, you might be doing well with *five* thou accuracy. And b) often the hex heads on fasteners are poorly aligned with the shanks. Consider what the function of the hole is to be, before deciding what is to be aligned *with*.
The easiest, fastest way: a lathe.
If you do it on a drill press, here is one way to come close: swing the table off to the side, and clamp a thick aluminum plate so it overhangs under the quill. Carefully centerdrill a starting hole, and enlarge it to the size of bolt you you are using.
Without moving the table, fasten the workpiece into the hole and repeat the process - the hole is roughly aligned with the quill's axis. The tighter the fit of the bolt in the hole, the better you will do in terms of accuracy. For this aproach, +/- 0.010 inch is about the best you can hope for.
Jim
It's rather unlikely that his "small" drill press has a 3/4" chuck, and that's what's needed to span the head of a standard 1/2" hex bolt.
You're a better and braver man than me Dave. The heads of garden variety bolts aren't exactly precision machined features. Whenever I've tried to chuck a hex bolt by its head in a 3-jaw the wobble at the business end of the bolt was humungous!
SWMBO just asked me to take the kitchen garbage out, so on my way back I ducked into my basement shop and stuck a couple of brand new 1/2-13 x
1-1/2" bolts in the 3-jaw on my little Stark lathe to check my memories. TIR at the ends of those bolts was about .08" for one and over .11" on the other. (I know that my chuck ain't great, but it's not *that* bad.)But, "pretty is as pretty does" so if it's worked for you Dave then G-d bless 'ya and I'm not gonna sit here and tell you that it won't.
Cheers,
Jeff
Thanks everyone for your kind replies. The project is for a supercharger pulley puller/installer that I am constructing. The
5/8"-18 bolt acts as the forcing screw and the hole is to put a press fit locating pin (which, in turn, mates with the supercharger shaft). Trying to stay on the cheap and use basic materials/techniques as opposed to purchasing a 150+ dollar puller. Thanks again.
Good luck to you on this. I recently made a camshaft sprocket puller for a GM DOHC V6 out of an old floor jack cast iron wheel and some latheing and brazing. The serv. mgr. at the local dealer was good enough to let me take some pictures of the outrageously expensive GM special tools. And I thought DaveK's method of centering your hole was just clever as hell. Learn something new here every day.
Garrett Fulton
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.