Thoughts on 1018 steel vs. 1022 et al

[Joe Gwinn]

You drill through tape, I take it?

Yes.

I assume the steel dowels would be to hold the stock and template in place length-wise?

That's one way, but I was imagining that the pocket was tight enough to constrain the location of the piece being drilled, and so all the dowels do is to ensure that the template is properly located with respect to the pocket. It's a good idea to arrange things so the template fits on the wood in only one way, to cut down on bad drilling due to confusion.

I've got some brad points and some others that look a bit like split points that really cut through steel like butter. But yes, bits sure do like to wander. My drill press is not super high quality and wobbles a bit on its own, but I think a good jig and template should keep it in line.

I'm not sure what you mean by brad points, because real brad-point drills are intended for wood only. Here's what they look like: McMaster-Carr

There is a kind of drill called a pilot-point bit that looks like a spur drill but is intended for metal. The difference is that the central spur isn't sharp, and there are no edge-cutting spurs.

And for split point bits look at picture 7 in Metalworking Basics - Popular Mechanics.

And some general information: Drill bit - Wikipedia, the free encyclopedia.

The split point drills are very good in steel, and one can greatly reduce the wandering by using very short drill bits. These short bits are called "screw machine" drills or lengths, and are roughly one half as long as the "jobbers length" one has in most sets. This matters because flexibility (and thus propensity to wander) varies as the cube of length, so half the length is eight times the stiffness.

As one will be drilling steel with coolant, the black oxide finish is best.

And while High Speed Steel (HSS) alloy is very good, for this kind of repetitious drilling a cobalt alloy bit will work even better. The cobalt HSS alloys are called M42 and the like.

So, we want a cobalt HSS bit with split point and in screw-machine length, with black oxide finish.

The only remaining decision is the angle of the tip, 135 degrees or 118 degrees. Either will work, and one or the other will have less tendency to wander. I would try both and see if it much matters.

Yes, drill bits meeting all these requirements do exist, and are in fact common. MSC's website is down, or I would provide a pointer.

More good points. I've had a few items catch and it isn't pretty.

Anything used in production should have safety designed in, as being careful is too unreliable, especially as one becomes bored.

[Joe Gwinn]

A machinist/friend built this for me. The guide is hardened. Not perfect, but the results are much better than the typical stamped fare.



Use jobber split point stub bits. I buy flat stock, typically 1018, and cut it to length with a Rage2 chop saw (has a TCT blade instead of abrasive - nice clean cuts w/minimal sparks and heating). The tomato sauce can has a large washer glued to the bottom to prevent tipping. Black thread cutting oil to drill. YMMV.

I like it. I have a machine shop, so I would do something like this, right down to the hardened template.

I have built hardened drill templates for people. The hard part was getting all the holes exactly where they belonged. This requires the use of a mill. Hardening the steel is easy, and can be done by anybody with a torch and a dark basement.

As for the can of black sulfur oil and the brush, flood cooling works far better than daubing, and is worthwhile if one is doing a lot of drilling. I have a coolant pump for my drill press, but one can build the fixture to live in a seamless aluminum baking pan, which is filled up such that the workpiece is underwater. Soluble oil coolants work very well, and are less messy than oil.

[belwar]

I've made about 2000 keepers so far on the CNC, and have tried all kinds of various drill bits.

I do a two stage drill which takes longer, but the holes are DEAD center. I use a center drill first and go about 0.02" deep. This creates a basic center mark for the main drill bit to line up with and self center.

The center drill bit looks like this:

http://www.mcmaster.com/param/images...s/27445a15.gif

Then I follow up with the correct size drill bit for the hole. I like to use the Cobalt Steel stub length with the TiCN coating. The stub length is great to reduce vibration and increase rigidity which decreases wandering.

McMaster-Carr

When I started making them, I went really slow and peck drilled. I drilled the hole undersized and then went back and finished them with a chucking reamer.. However as time went on I dropped the reamer from the process and got rid of the peck cycle and plunged straight through in one shot. I can get about 1000 keepers before I replace the drill bit. That's 6000 holes.

Black oxide is good for low volume, but the Ticn is just wonderful if you can afford it.

[Joe Gwinn]

I've made about 2000 keepers so far on the CNC, and have tried all kinds of various drill bits.

I do a two stage drill which takes longer, but the holes are DEAD center. I use a center drill first and go about 0.02" deep. This creates a basic center mark for the main drill bit to line up with and self center.

Then I follow up with the correct size drill bit for the hole. I like to use the Cobalt Steel stub length with the TiCN coating. The stub length is great to reduce vibration and increase rigidity which decreases wandering.

When I started making them, I went really slow and peck drilled. I drilled the hole undersized and then went back and finished them with a chucking reamer.. However as time went on I dropped the reamer from the process and got rid of the peck cycle and plunged straight through in one shot. I can get about 1000 keepers before I replace the drill bit. That's 6000 holes.

Why is such precision needed in a keeper bar?

The templates I made were for drilling the holes to hold the bushings where the strings are attached to the guitar body, and accurate alignment was required for looks, but not for function.

No center or pilot drilling was done - just dive in. The template was able to completely control where the drill bit went. For making keepers, I bet one can do the same, if the jig is built well enough.

[belwar]

I think im just a precision nazi :>

The center drilling cycle adds about 30-35 seconds a keeper bar, but it extends the life of the standard drill bits because they dont wander off.

Joe, I didnt know you had a machine shop. What kind of tools do you have?

[kevinT]

This is a great thread. After reading it I am thinking more about making my own keeper bars instead of having them customed machined. After possum described his ordeal with making his own slugs with his lathe, I thought that it was really time consuming and a royal PITA. But I'm thinking twice about it now. My keepers are costing about $2 a pop.

I know Spence has recommended the miter saw below. Do you think that it would work well with cutting solid stock?

MINI MITER / CUT OFF SAW


What about this milling machine. What are you all's thoughts on this machine's ability to produce keeper bars?

MICROLUX BENCHTOP MINI MILLING MACHINE, ALL INCH MINI MILL

[kevinT]

BTW, Skinny, that is a nice jig setup that you have. Your keepers look really nice.

[David Schwab]

I know Spence has recommended the miter saw below. Do you think that it would work well with cutting solid stock?

MINI MITER / CUT OFF SAW

It's a nice machine, but look at the price. I'd rather have that Rage saw mentioned earlier, or the one I got, which is pretty much a larger version of the Micromark as far as functionality. And for $40.



- Harbor Freight Tools - Quality Tools at the Lowest Prices

I cut through 3/4" x 1/4" steel bars like butter. Then I just have to de-burr the edges on a grinder.

[Zhangliqun]

Joe, I found a crude way to make a jig last night. I drilled two pieces of 3/16" thick bar stock each with a hole at both ends and screwed them into a block of wood with another piece of 1/8" barstock (the keeper-to-be) in between them to ensure a snug fit. Then a screw at either end to hold it in place length-wise and a Stewmac keeper bar on top as a template, held in place by the end screws and the fact that the 3/16" stock is taller holding it in place width-wise.

Though the design needs some refining, it worked really well for a single piece, certainly many orders of magnitude better than anything I've done before at least.

Will take a closer look at the bit tips tonight to verify what type they are. But they cut 1018 steel like butter, that's for sure.

[Zhangliqun]

It's a nice machine, but look at the price. I'd rather have that Rage saw mentioned earlier, or the one I got, which is pretty much a larger version of the Micromark as far as functionality. And for $40.



- Harbor Freight Tools - Quality Tools at the Lowest Prices

I cut through 3/4" x 1/4" steel bars like butter. Then I just have to de-burr the edges on a grinder.

If it cuts steel that well, I will look into it too. Good tip...

[belwar]

Do you guys want to see the CNC setup that I use to make them? If theres interest i'll take some photos and video of it and post it for y'all to see. It's nothing pretty but it gets the job done.

[kevinT]

That would be great....would love to see it.

[belwar]

Attached are some pictures of the tooling in the machine. Note that I am aware of the small ammount of rust. They sat wet all weekend by accident and need to be cleaned up with steel wool.

Here's a video of the process.

YouTube - 50mm Keeper Bars

The cycle takes 5 mins for 3 keeper bars. You'll either get bored, or be mesmorized when you watch the video. It's four steps to make them.

1) Center Drill
2) Mount Screw holes
3) Pole Screw Holes
4) Trim to length.

After they come out I clean them up with hand drill and a countersink to deburr them. There tends to be a small burr on the bottom side of each hole. I could tumble them to get rid of them, but its faster to just take a dull countersink to it.

The vise is located by special dowel pins to the table, then I have two steel bars which butt up against one side of the vise. This controls the X & Y positioning. It's a super low tech method that works well for low to mid volume. I would make a real jig if I were going to make many, many, more.

[kevinT]

that is awesome....the process and the machine. That CNC machine, i bet, was a pretty penny.

[Joe Gwinn]

Joe, I found a crude way to make a jig last night. I drilled two pieces of 3/16" thick bar stock each with a hole at both ends and screwed them into a block of wood with another piece of 1/8" barstock (the keeper-to-be) in between them to ensure a snug fit. Then a screw at either end to hold it in place length-wise and a Stewmac keeper bar on top as a template, held in place by the end screws and the fact that the 3/16" stock is taller holding it in place width-wise.

Though the design needs some refining, it worked really well for a single piece, certainly many orders of magnitude better than anything I've done before at least.

Most jigs are pretty crude looking, but do the job. Sounds like this one works just fine. After some experience, you'll have ideas for the 2nd generation jig.

Will take a closer look at the bit tips tonight to verify what type they are. But they cut 1018 steel like butter, that's for sure.

Yes, they do. But they do need the coolant flood or at least puddle.