Greenlee Punches

[dirtyhanfri]

I use a transfer punch and a stepped bit, with no drill stand.

I start with the laser engraving of the pannels, I add a point in the center of every hole. Then I punch them with a transfer punch, put tape on it and drill 1mm holes using a Proxxon rotary tool with vertical stand, then 2mm, 2,5 and finally 3,2mm,  I use a big drill with a stepped bit, by hand, having the 3,2mm gives you better accuracy, as you can insert the tip of the bit and helps keeping the hole straight. Also I put a piece of tape on the bit as a size reference.

 

[usekgb]

I picked up a Craftsman 12" drill press to use with a stepped bit, and have found my accuracy to be much better.  Another advantage to the stepped bit is that it can de-bur the holes that you drilled.  For doing xlr holes though, nothing beats a punch!  You can drill out smaller holes for the pull bolt, and just finish with the punch.  Nice clean holes every time.

 

[Gold]

Here is how I use combination squares

Here is a mark. The lines are scribe marks and the dot is the center punch

Pilot holes

Transfer Punch

Time to walk the dogs.

 

[abbey road d enfer]

My panel drilling/punching steps:

1.  Apply masking tape to the panel.

2.  Using a metal ruler which is marked with 1/32" increments, lay out various "grids" for the various holes on the masking tape with a fine-tipped ballpoint pen.  I also make a note on the masking tape of the final hole size, be it drilled or punched.

3.  For each hole to be drilled, use an awl (pointed tool, with a tip that looks like a small nail) and a hammer to tap an indent through the crosspoints on the masking tape, and thus an indented "dimple" onto the underlying metal piece.

4.  Drill 1/16"  pilot holes using the indents made with the awl.

5.  With pilot holes drilled, then finish each hole with the drill to the final desired size.

Use a piece of wood behind the panel while drilling.  The masking tape also serves as a surface protector for the panel while drilling.

My holes are always perfectly located...if I laid it all out correctly in "step 1"  <g>

As I mentioned, my Unibit skills are my weakness, since I seem to invariably drill out the holes with too large of a diameter.  Hence, my large collection of Greenlee punches.

Bri

Professionnally, I use a subcontactor using CNC, but for my own gizmos, I use a variation of your method. I print a drawing done with Autocad (for those who don't have Autocad, there is now Draftsight, which is 100% compatible, and free), that I glue on the panel with school glue.
I think many beginners make a number of mistakes, like starting with too big a drill bit. I never start larger than 3mm (about 1/8th), so even if the hole is misplaced I can draw it with a needle file.
Remember to drill the hole in several passes, increasing the size all along. Doing so allows drawing the hole manually if it's out of place.
Another common mistake is not supporting the panel correctly. The panel must be supported on all its length by a piece of wood (we call it a "martyr") that will help get the panel flat and stable.

 

[mobyd]

If you're making more than one of them, make a template - then they will be all right or all wrong, but at least they'll be all the same.

 

[bendayho]

Hey all. some great tips in this thread.

I'm trying to make some panels for a bunch of the mutable instruments synths and I'm having a bit of a hard time getting my holes precise and repeatable.

I use a similar process described by others in terms of layout / scribing / punching my workpiece, and have experience with that type of handwork. I have no problems marking it up with the accuracy I need, however I'm having a bit of trouble getting repeatable accuracy when clamping down the piece and lining up with the drill bit.

I'm using a drill press with a table and fence and a uni bit (part of the issue I think is that setting the tip of the unibit into the dimples I punched doesn't always seem to equate to exact hole placement.)

Someone above mentioned that they start off drilling smaller holes first to allow them to "draw it with a needle file" (not sure I understand what abbey road d enfer means by "draw" ), but wouldn't I have the same problem of not being able to line up either the initial hole or then the unibit with the smaller hole, especially if it ends up being off?

One thing I tried was scribing a vertical line on the actual fence that lines up with the drill's centerline, and then adding marks along the top of the workpiece so that I can line up the workpiece to the fence along one axis, this helped reduce slippage on once axis (vertical) but still having issues on the other axis (horizontal).

To get sense of what I have to drill: https://www.dropbox.com/s/hhx1xoyy5w9kc2v/Screenshot%202015-01-14%2011.55.08.png?dl=0

the larger holes are for tact switches and the small holes are for leds.

Any help greatly appreciated!!

 

[abbey road d enfer]

Someone above mentioned that they start off drilling smaller holes first to allow them to "draw it with a needle file" (not sure I understand what abbey road d enfer means by "draw" )

Draw like pulling, not like sketching. That means using the needle file to center the cirle properly.

, but wouldn't I have the same problem of not being able to line up either the initial hole or then the unibit with the smaller hole, especially if it ends up being off?

The whole idea is to put the enlarged small hole centered exactly where you want it, then the larger bit should drill a perfectly centered hole.
After re-reading your post I think you're skipping the most important part: the pilot hole.

 

[warpie]

Pilot hole is the most important thing to do before drilling your required diameter.

The problem (that I have yet to find a DIY solution) is when you want to drill small rectangular holes for these pushbutton switch cups (like these for example)…

I don't think there are any punches for such small dimensions  :

 

[bendayho]

Someone above mentioned that they start off drilling smaller holes first to allow them to "draw it with a needle file" (not sure I understand what abbey road d enfer means by "draw" )

Draw like pulling, not like sketching. That means using the needle file to center the cirle properly.

, but wouldn't I have the same problem of not being able to line up either the initial hole or then the unibit with the smaller hole, especially if it ends up being off?

The whole idea is to put the enlarged small hole centered exactly where you want it, then the larger bit should drill a perfectly centered hole.
After re-reading your post I think you're skipping the most important part: the pilot hole.

Thanks for clearing that up, I think your right regrading skipping the piloting hole step being the problem. Will give it another go, starting with an 1/8" pilot.

Thanks again!

 

[Gold]

You will undoubtedly have a great improvement using a pilot hole. For further refinement you may want to get a few center punches with different tip diameters. You can start with a small punch mark. If it's a little off you can move it slightly with a larger mark.

I'll put in another plug for the magazine Home Shop Machinist. The back "shop class" article deals with exactly this.

 

[bendayho]

You will undoubtedly have a great improvement using a pilot hole. For further refinement you may want to get a few center punches with different tip diameters. You can start with a small punch mark. If it's a little off you can move it slightly with a larger mark.

I'll put in another plug for the magazine Home Shop Machinist. The back "shop class" article deals with exactly this.

I totally already had the link up in a tab from your earlier post 

 

[bendayho]

Pilot hole is the most important thing to do before drilling your required diameter.

The problem (that I have yet to find a DIY solution) is when you want to drill small rectangular holes for these pushbutton switch cups (like these for example)…

I don't think there are any punches for such small dimensions  :

I hear you! the ambika and the anushri both had those, I just opted to go with the round switch caps and bypass the issue that way  8)

 

[bendayho]

After giving it another go yesterday I've come to the conclusion that while I will from now on start with a pilot hole, this is not the issue I'm having.

I'm still getting quite a bit of wandering even with the center punch, which leads me to believe as Gold suggested I need to start with a finer center punch and move up to a bigger punch that will make a larger dimple so that the bit doesn't wander, does that sound right? Wondering if thats why I'm not getting consistent results even with a smaller bit (which has a tendency to wander even more)

 

[BYacey]

I always cover the entire panel surface with masking tape to protect it and for laying out the panel with a fine felt pen.

After center punching where you want the hole centers to be, drill them with with a 1/16" to 1/8" bit; make sure it's a sharp bit so it cuts evenly and doesn't wander. A split point cobalt steel bit is best in this respect. Mark a cross grid (90 degree) across the center of each hole . Many of the greenlee punches have index marks on the outside of the punch that allows it to be accurately centered to a cross grid, even if the drawbolt hole is oversized. After everything is laid out and the pilot holes are drilled, you can drill the holes out bigger with a 25/64" bit. This larger size will allow the punch to be aligned to the grid markings and makes it easier to remove the slug off the drawbolt afterwards.

I only use a unibit for holes that don't need to be aligned or accurate. These bits cut very aggressively and tend to wander off from the original center because of the way they cut. They wander with each successive step increment of the bit. I feel they are only suitable for hacking out knockout holes in electrical boxes.

Always ensure the drawbolt threads are well lubricated with a machine oil;  I apply some for every hole  punched. If you do so religiously, the punch will last for years. Try and get a drawbolt with a thrust bearing, it cuts with a lot less effort.

 

[abbey road d enfer]

I'm still getting quite a bit of wandering even with the center punch, which leads me to believe as Gold suggested I need to start with a finer center punch and move up to a bigger punch that will make a larger dimple so that the bit doesn't wander, does that sound right? Wondering if thats why I'm not getting consistent results even with a smaller bit (which has a tendency to wander even more)

I have never seen "a smaller bit (which has a tendency to wander even more)".
In my universe, smaller bits do wander less than larger ones.
Indeed the punch must be large enough to properly guide the drill bit, but I've never resorted to a bigger punch.
Maybe you don't realise that the punch can be "drawn" too. By using careful slanted blows, a punch that has started off-center can be put right in place.
I usually use a 3mm (about 0.125") bit except on specific cases - one being 3mm LED arrays, where I would use the same standard punch with a 2mm (ca. 0.08") bit.
I have found that in most cases, wander is less than 0.5mm (0.02"), so I make sure that, for small holes, the bit diameter is 1mm less than the final hole, which allows me to "draw" the hole with a needle file in case the bit wanders - which will happen in about 10% of the cases.

 

[bendayho]

Many of the greenlee punches have index marks on the outside of the punch that allows it to be accurately centered to a cross grid, even if the drawbolt hole is oversized.

I'm not sure if this was for me or not. My only issue with greenlee punches is that I didn't think they came in anything smaller than 1/2"

 

[Gold]

For small holes, besides the imperial fraction inch there are machinists numbered bits. They are numbered 1-60 in many sets and are in decimal inch. They get smaller as the number goes up. There are very very fine ones in the 80's. These are in small increments. It takes a lot of patience but you can get better accuracy. When you try to do big holes you need very fine increments. That gets expensive.

I'd also recommend short length drill bits. They are much stiffer, much straighter holes.. You don't need much drill blade to go through 1/8" aluminum or 20 ga steel.

 

[abbey road d enfer]

I have no problems marking it up with the accuracy I need, however I'm having a bit of trouble getting repeatable accuracy when clamping down the piece and lining up with the drill bit.

I'm using a drill press with a table and fence and a uni bit (part of the issue I think is that setting the tip of the unibit into the dimples I punched doesn't always seem to equate to exact hole placement.)

Someone above mentioned that they start off drilling smaller holes first to allow them to "draw it with a needle file" (not sure I understand what abbey road d enfer means by "draw" ), but wouldn't I have the same problem of not being able to line up either the initial hole or then the unibit with the smaller hole, especially if it ends up being off?

OK, I think I understand your problem. You're trying to align the tip of the bit with the punch, with the piece clamped down stiff. I guess you're using the table and saddle wheels to position the workpiece, aren't you?
I would say it's not the best practice. I always have the workpiece free, supported flat on a wooden martyr, where I can easily move it and allow the tip of the bit to follow the punch.
Using the wheels with standard drill bits is doomed. It works only with specific cutters that have less flexibility than standard drill bits.

 

[Gold]

I guess you're using the table and saddle wheels to position the workpiece, aren't you?

This will never work. I've been there.  A drill press is not a Bridgeport mill no matter how much you want it to be,

 

[BYacey]

It all comes down to accurate layout, and accurate drilling.

Accurate drilling is only possible with a well defined center punch mark, followed by drilling with a sharp split point bit.  With experience, it's possible to drill accurately with a hand drill, but a drill press is the tool of choice.  I don't clamp my workpiece unless it's very small, or I'm drilling with a large bit that can grab the workpiece.  As I mentioned in a previous post, accurate punching is only possible if using the index marks on the punch to center it, or by very accurately drilled holes exactly the diameter of the drawbolt. The only problem with drilling tight exact sized holes, is that it's difficult to remove the slug from the drawbolt afterwards.