[pminmo]

Would like to find an online tutorial or webpage on best simple methods to layout drill patterns precisely.

[DieGuy]

THe best way I now of to manually lay them out is to have a angle plate, surface plate and a height gage. Lay out one axis heights then turn 90 and run the other heights.

[Geof]

Would like to find an online tutorial or webpage on best simple methods to layout drill patterns precisely.

What kind of patterns are you talking about? Circles, lines, rectangles, ? All in the same plane or in different planes on the same part?

[pminmo]

Same plane. 6061 plate. For example two holes, offset and parallel to an edge by .500 in and a specific distance apart 4.250. I have machinist squares 6" and 4", (4) 123 blocks, a 6" digital caliper with .0005 resolution, and a 4" angle plate. Good drill press and center drillls. I'd like to get to +/-.002. Is that to much to ask for?

[ZachB]

Yes I would think +/- .002 is to much to ask for, considering what you have to work with. I would get a good 2 axis stage for your drill press and a edge finder and you should be able to hit your tolerances, without having too dicey of a setup.

[Geof]

I second that: for manual layout using a center punch, center drill and drill sequence +/-0.01 is more realistic.

[pminmo]

I also have taps and dies, center punches, feeler gauges, small metal lathe. It would seem I could rig something up to do better?

[ZachB]

If you got creative you probably could jig somthing up on your lathe, by mounting your part to an angle plate to the cross slide, but you really need another stage to dial the Y axis in to get the tolerances your looking for. Its doable but personaly i like to use the right machine for the right job.

[Mcgyver]

with a scale, .01 is probably the limit...but with two more pieces of equipment you can get to layout accuracy of .002 manually. that is an optical centre punch and height gauge. If you don't have surface place the drill press table will do. Reinforce the mark from the optical with a manual centre punch and start the hole with spot drill instead of a centre drill.

I've an On-mark optical punch and like it a lot, and a cheapo$100 height gauge that has served me well. Maybe you don't want to buy more tools (but who are we kidding right?) but manual work of this accuracy is possible

The other consideration to accuracy is that the holes require and x-y coordinate, when you index the work 90 degrees to move one from the other, the piece has to actually be an accurate 90 OR bolt to something like the 123 and index it

there is another way to do it that will get you better than a thou using using tool makers buttons (which you make). I can explain it or take some photos if you really need super accuracy but its a lot more work for you and requires you boring the holes in the lathe or mill - don't know if the job will fit in your 4 jaw

[Halfnutz]

I just got my DRO up and running on my HF Mill/Drill. I got a read head for 60.00 off ebay, and then spent 175.00 learning how to buy garbage scales that dont work. Finally I scored a brand new 500.00 Heidenhain 20" scale for 115.00, but found out it was the wrong output signal, and had to buy a interpolation box . Found it (Hiedenhain 602 D5-F) for 100.00 on ebay, plus another 70.00 for a cable. The Y axis was scaled with an RSF open glass scale for 30.00 plus 70.00 for the cable. I put a cheap Chinese Mitutoyo style digimatic quill kit on the Z for 40.00 off ebay. The total comes to 660.00. I would have been way better off buying a complete DRO for a little more with a warranty and around 3 weeks less jerking around. You live and you learn. Now I can co-ordinate down to +/- 0.0005" and it is so nice. I cant get over how accurate the thing is, it blows my mind (and blew my bank account as well).

How can you do it cheap? Good question.

Tip - Dont buy glass scales off ebay unless there warranted and EXACTLY what you need with cables. (there are three different output signal types made)

(The above opinions are the authors and do not represent those of CNCZone or its management.)

[pminmo]

Is a spot drill ground differently than regular drill bits? BTW, one point in my endeavor I forgot to mention. Absolute accuracy isn't as important in my situation as parallel and distance repeatability. .01 off absoute isn't a problem as long as I can repeate the parallelism and distance. Dose this make a difference?

[ger21]

Cant you mount a fence to your drill press. Use some scrap to fine tune the location. And use stop blocks for location in the other direction. If you're making a bunch of parts at the same time, this will get you good results. If you're going to make 1 every week or two, it won't help you much.

[DieGuy]

If this is something you are going to do on a on going basis then a drill jig is a good investment. Then you only have to get the hole pattern right one time and it might pay to find someone with a mill to do the alignment in the jig.

[pminmo]

I've tried the fence and stops with reasonable results. My drill press is tight, with minimal measurable runout on a dial indicator. I believe what I truely need is a bit like a centering bit, but has a fine point that once it hits the aluminum, there is NO deflection on starting.

[Mcgyver]

Phil, DieGuy is right, if you've a lot to do, make a drill jig. Or, take the first one you make, with accurately reamed holes, and use it to transfer the hole location to subsequent ones using homemade (from drill rod) transfer punch. This is really easy and accurate.

A spotting drill is the same idea as a centre drill, short and stubby. Either will pick up the centre punch mark but the spot drill is the right tool as it leaves a 118 degree cone shaped hole perfect for the drill bit to pick up vs the 60 centre drill hole that can chatter when you are finding the hole with a drill bit

[Geof]

If you are doing more than one and it is worth making a bit of tooling you do not even have to worry about the position accuracy of your guide holes. I have attached a sketch (I hope). You need three pieces of flat bar: drill your guide holes accurate to size in two pieces as shown and also drill a good clearance bolt hole near the other end; in the third piece drill two bolt holes as close as you can get to your required spacing and back from the edge the appropriate distance so this piece serves as a fence for your workpiece. Assemble this template and adjust the two guide hole pieces to get the correct spacing and distance from the fence piece; you have more than adequate measuring instruments for this. Now you have a template that is far more accurate than you could ever make out of a single piece. Maybe drill extra holes alongside the bolt holes to lock everything together. If you want to use this as a drill jig instead of a template just buy or make some hardened bushings the correct size and make your guide holes to fit the bushings. Even if you are only doing one piece going through this template making procedure may be worthwhile.

[pminmo]

Geof, good suggestion. Suggestions on making hardened bushings? I've turned drill rod frequently, is it be hard enough for casual usage?

[ger21]

Suggestions on making hardened bushings?

McMaster-Carr has them for pretty cheap. I use them to make jigs for mounting cabinet hardware.

[DieGuy]

Geof, good suggestion. Suggestions on making hardened bushings? I've turned drill rod frequently, is it be hard enough for casual usage?

Plenty hard enough. I personally like O1 drill rod for these quick jobs because it is pretty forgiving on the hardening. Just heat it up to a nice low red color and quench in a can of oil. The polish off the crude with some emery and draw them back by heating until a light straw color. It should come out around the high 50's Rc. Just remember it will grow slightly when hardened.

Edit:
Use at least 2 bolts on each of the connections for the Jig, when it is aligned to your liking just add a couple of dowels to each connection to make it permanment, Even a couple of roll pins in a drilled holes should be good enough to hold your tolerance numbers. Also make a pin to fit in the fisrt drilled hole to help keep the jig in alignment.

[Geof]

The only additional bit of advice I have is if you are going to go the drill jig route just enhance my suggestion by adding some sort of clamping to hold the part. Alternatively set it up on your drill press clamped in place so you have the drill coming down through one hole and then flip the part and locate it with a pin in the other jig hole for the second drilling. On the drill bushings I use W1 because I don't like the smell and fire hazard of oil quenching and I never temper the bushings but these are personal preferences. One thing you should ensure is that the bushing comes into firm contact with the workpiece and has a perfectly sharp corner. Any gap or chamfer here allows chips to wedge between the bushing and workpiece especially with 6061.