Machine Shop Practice: Making Custom Metal Hardware For Basses

[Bruce Johnson]

I have not researching indicating your vise extensively but this video (part of a whole series) seems like a good starting point:

Yes, she does a good job covering the basics of "Indicating In" a milling machine in that video.

I haven't watched more of her series of videos, but they look like they are well done. Classic machine shop technique, taught simply for hobbyists with their first small machines.

Any of you who are getting the itch to get a milling machine or lathe should watch her videos as an introduction.

 

[BTL]

[...] It looks like this Weldon bit might be just the ticket to countersink for #3 wood screws into mild steel. Agreed, or is there something better I should be looking at?

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I ordered two of these bits just to have on hand...a bit spendy but it's precisely the right tool for the job. I was unable to find another vendor who had it in stock and would ship, so I bit the bullet and ordered from MSC.

I'm really looking forward to putting these to good use. Thanks, Bruce!

 

[Bruce Johnson]

I ordered two of these bits just to have on hand...a bit spendy but it's precisely the right tool for the job. I was unable to find another vendor who had it in stock and would ship, so I bit the bullet and ordered from MSC.

I'm really looking forward to putting these to good use. Thanks, Bruce!

Yes MSC is a good company. They've been around since the '70's. A good source for specific machine shop tools and supplies. Also, they tend to carry both the top quality expensive stuff, and decent quality imports. Side by side, your choice, with explanations of the differences. They don't carry the really cheap, barely usable stuff. I like that model as a distributor company.

 

[Flamingo21]

I'm trying to source a Spot Drill, and the biggest problem with that is finding out what the heck they are called in my language. Experience has shown that for most objects that are somewhat specialist, the Dutch and English word are either the exact same or so wildly different that you would never guess it. Online translators and the like are useless, they all give the obvious (and wrong) answers. I have run into this problem with many Luthier's Corner threads. Why did I join an English language forum again? Don't answer that.

End of rant. Can someone show me some closeups of Spot Drills? That would help with the search. Thanks.

 

[Jeff Siddall]

I use a Whiteside 1500 90° V-Groove Bit. That one is solid carbide and relatively inexpensive. I think you can use anything that is rigid (i.e.: short) for spotting but @Bruce Johnson will know for sure.

 

[T_Bone_TL]

Can someone show me some closeups of Spot Drills? That would help with the search. Thanks.

McMaster actually brings up "hole starting drill bits" when you search for spotting drill. That's another description of their function. Short, stubby, short flutes, yep.
McMaster-Carr
McMaster-Carr

MSC does seem to refer to them as spotting (not spot) drills:
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And I don't know what the equivalent suppliers in Europe would be. Both are metalworking/machining suppliers who also have a mail-order/web presence.

 

[Bruce Johnson]

Moving on in the subject of doing Machine Drilling in a Milling Machine:

Back to the DeTemple aluminum bridge bases. Some pages back, I showed how I had sawn off the blocks, then milled them square and to the correct length. The next step is to drill all the holes in the blocks, while they are still full accurate rectangles.

Here's a quick preview of what I'm going to do. On the left is one of the blocks after I've finished drilling all the holes. On the right is the sample part that I'm copying. The reason why I'm drilling all the holes first is that it's easier to place them all accurately in a full rectangular block, than it would be to lay out and drill them on the shaped part. I almost always do this on parts like this: Drill all the holes before doing the milling and shaping.

I've got the Green Mill/Drill all set up for Machine Drilling, as I described on the previous page. The vise is indicated in, with parallels and a stop. I used one of the blocks and the Pin & Flashlight technique to zero the DRO's on the right rear corner. Check. And I've got a printout of the AutoCad drawing showing all the X and Y Ordinate locations of where the holes are supposed to go. Okay, I'm kidding. On this job I actually have an index card with a crude pencil sketch and all the numbers written in with lines and arrows. As measured from the sample part.

So, here I go with the Machine Drilling. I drop the first block in the vise, on the parallels, seated against the stop on the right. Crank the X and Y of the table to the location of the first hole, based on the DRO's, lock the table. And put a big Spotting Drill in the drill chuck........

Wait, What? A Spotting Drill?......This gets a little confusing.....

I already explained the difference between the Spot Drilling process and the Machine Drilling process. When Spot Drilling in a drill press, we leave the vise loose to slide around, and use a Spotting Drill to kick the centerpunch mark into alignment with the spindle.

Well, when Machine Drilling in a Milling Machine, you adjust the table and vise to the accurate position, with the DRO's, and lock it down. Then, you put a Spotting Drill in the chuck, and bring it down into the metal. That puts a Spot in the correct position, aligned with the spindle, and locked down. Then, switch to a Screw Machine Drill to start drilling the hole. The Spot's purpose is to make absolutely sure that the Screw Machine Drill goes in straight and true. This is classic Real Machinist technique, to make sure the hole ends up within 0.001" of where you set it on the DRO's.

When Machine Drilling, you don't have to use a Spotting Drill first. A good sharp Screw Machine Drill will usually go in quite straight by itself. That's what it's designed to do. Putting a Spot there first is just an extra bit of insurance. I usually don't Spot when doing Machine Drilling in the drill press, like I showed in some of the examples a few pages back.

On these DeTemple bridges, I decided to take the extra time to do the spotting to make sure that all these holes are lined up accurately. On a part like this, where there's a straight line row of holes, any one hole that's even a few thousandths' out of line sticks out visually. One bad hole can ruin the part, and waste a lot of work.

This is something to watch out for in metalworking, making custom hardware for basses. If you design your part with hole patterns to be straight in line and rectangular, then you have to place them with extra accuracy. Or they will look bad. If you are making an odd-shaped piece, and you deliberately make the screw hole pattern non-orthogonal ("artistic") then you can get away with a little more error in hole positioning when you make the part. Something to consider when you are making that one-off custom tailpiece.

So, here I am, making Spots at every hole location, on all the blocks. Exactly to the DRO readout locations on my index card. Same sequence as I showed when Machine Drilling in the drill press. I set the location via the DROs for one of the holes, and spot that one hole on all 11 blocks. I'm rapidly switching parts in the vise, maybe 5 seconds per part. Move the table to the 2nd hole location, repeat 11 times. Etc. All the holes on all the blocks.

Here are the 11 blocks with all of the holes on the top face spotted.

And then I go through and repeat the whole cycle, but now with Screw Machine Drills in the spindle. 1st hole on all 11 blocks, 2nd hole, etc. There are two different size holes here, of only slightly different size. So I have to be really careful to use the right drill bit in each hole. You definitely want a good precision keyless drill chuck for your milling machine, so you can change bits in seconds.

Here's the 11 blocks after drilling all the holes through from the top surface.

Here's one of the tricky parts of these DeTemple bridges. On the angled back surface, there are cone-shaped recesses that are necessary for clearance of the screw heads. They have to be accurately placed and consistent to look good. The way to do that is cut a counterbore during the Machine Drilling process. I slip a small end mill into the chuck and go back to the exact locations of those three holes. This is the way to do a neat flat-faced counterbore; plunging an end mill down into a pilot hole. Accurately located in a milling machine.

Here are the blocks after doing the counterboring.

Then I turn the blocks up on edge in the vise. Same setup as before, parallels, stop. The 0,0 remains set to the same right rear corner, but now it's the bottom rear corner of the block.

I go through the same procedure to drill the four intonation screw holes into the back, only about 1/2" deep. Planning ahead carefully allows me to flip the parts in the vise like that and keep the same zeroing.

And here's another look at one of the blocks with all of the holes drilled in it. As compared to the sample part.

Next up will be milling away all that extra aluminum.

 

[Smilodon]

I'm trying to source a Spot Drill, and the biggest problem with that is finding out what the heck they are called in my language. Experience has shown that for most objects that are somewhat specialist, the Dutch and English word are either the exact same or so wildly different that you would never guess it. Online translators and the like are useless, they all give the obvious (and wrong) answers. I have run into this problem with many Luthier's Corner threads. Why did I join an English language forum again? Don't answer that.

End of rant. Can someone show me some closeups of Spot Drills? That would help with the search. Thanks.

European languages tend to be a bit more literal when naming tools. I would guess Dutch is similar. I think you are looking for "Centreer Boor". Maybe. I don't know any Dutch...

 

[Flamingo21]

On a part like this, where there's a straight line row of holes, any one hole that's even a few thousandths out of line sticks out visually. (...) If you are making an odd-shaped piece, and you deliberately make the screw hole pattern non-orthogonal ("artistic") then you can get away with a little more error in hole positioning when you make the part.

This is the same thing @Freekmagnet told us in his thread last week, when he was talking about the placement of position dots on a fingerboard. He told us that with normal dots (meaning they're all the same size and precisely centered) if one of them is of by a little bit it will look bad. This is what gave him the idea for his quirky position dots:

I just noted the similarity between two things we're being told by two different builders, and wanted to mention it.

 

[Bruce Johnson]

This is the same thing @Freekmagnet told us in his thread last week, when he was talking about the placement of position dots on a fingerboard. He told us that with normal dots (meaning they're all the same size and precisely centered) if one of them is of by a little bit it will look bad. This is what gave him the idea for his quirky position dots:

I just noted the similarity between two things we're being told by two different builders, and wanted to mention it.

Yes, absolutely, that's a classic example of using artistic design to relieve the pressure of engineering tolerances!

If you didn't know it, Jeremy (Freekmagnet) rents a shop space from me, across the hall. He uses my big machines daily, and we have many long conversations about topics like this. He has more background in graphics and art than I do. I have more in engineering and machine shop. We're learning from each other.

 

[Bruce Johnson]

I'll show you all a few more examples of Machine Drilling in the milling machine. Some parts that I regularly make here in my shop.

Here, I'm Machine Drilling the corner holes in the neck plates I make for my Scroll Basses. These plates are 1/4" thick, sawn from 1/4" x 2" 6061 aluminum bar stock. I square off the blocks and mill a recess in the middle, then drill the holes.

Same process I described above; Green milling machine, parallels, stop on the right, zeroed at the right rear corner, pulling numbers off a drawing. One hole at a time, on all the plates. It's actually quite fast.

Here I'm using a special purpose drill bit that combines spotting, drilling and counterboring into one operation. It's sized specifically for #10 Socket Head Cap Screws. A big time saver to do it all in a single shot.

I make them in batches of 10 or 20 at a time, up to this point. All the machining is done. I store them away in a box.

When a bass is coming together, I'll pull one of these out of stock. Screw it down to this holding block, to clean up the top surface. Level it with a #4 Swiss flat file, sand it with 400 paper on a hard block, smooth it on a grey Scotchbrite wheel, clean up the edges on a deburring wheel.

This is what it looks like installed, with a little aluminum engraved name plate in the middle.

 

[Bruce Johnson]

Here's the first half of the process for making the tailpiece for my AMB-2 Scroll Bass.

It starts with a chunk of 1/2" x 4" 6061 aluminum bar stock. Sawn off to rough length on the cutoff bandsaw.

Set up in the vise, mill the ends square and to the final length....

Machine drilling the holes in the top, using that same special #10 Counterbore bit that I used for the neck plates.

Machine drilling the string anchor holes in from the back, with the block standing up vertically.

Bandsawing out the rough opening that the bridge fits into. I pre-drilled 5/16" holes in the corners during the Machine Drilling, to make it easier to bandsaw into the corners.

Standing up a stack of 6 of them, using an end mill to accurately cut the walls and floor of that front opening.

Set up in an angle fixture to mill the rounded slots for the strings.

On the left is the tailpiece block with all the holes, slots, and flat surfaces done accurately. From there, the block gets rough bandsawn on the outside, roughly rounded with a radius mill, then hand filed to shape and polished up.

As I explained way back in this thread, making custom hardware for basses is a mix of traditional machine shop precision work, and free-hand woodworking-type technique. This is a good example.

How long does it take? From bar stock to finished part, I've been averaging 2 hrs 20 minutes per tailpiece. So, it costs me about $130 in materials and labor. That's not bad, really.

And remember, I'm not paying that money out to buy the part. I'm making the part, as part of my job. When I sell the bass, I collect $130 as part of the selling price. That reimburses me for the aluminum and pays me for my time.

A unique piece of hardware like this adds value to your bass, and earns you money for your labor.

 

[Flamingo21]

I square off the blocks and mill a recess in the middle, then drill the holes.

Earlier you told us you generally drill into the block-shaped part, before shaping it. What is the reason for milling the recess first?

 

[Bruce Johnson]

Earlier you told us you generally drill into the block-shaped part, before shaping it. What is the reason for milling the recess first?

Hmm, I don't really remember why I mill the recess before drilling. On this part, it wouldn't really matter which was done first. There's enough side wall thickness that it clamps securely in the vise, and the milling doesn't affect that. I dunno.

 

[Flamingo21]

I went to the Shop with Knowledgeable Staff, and sure enough someone knew a Dutch word for "spot drill". I hope he got it right. I bought these:

I also bought an automatic center punch, a hammer center punch and a drill press vise.
(I made up "hammer center punch".)

The vise has quite a bit of wear, it has the chrome plating falling off in places. I hope it served its previous owner well. By the way, I checked that it slides freely on my drill press table.

My plan right now is to make a front control cover plate from 2mm brass, for my SBO project. At first I decided not to cut this on the band saw, because of the SparkleWood effect, but I find it very tough to cut by hand.

So now I'm wondering whether to cut it on the band saw after all, and defy the SparkleWood problem. Or, of course, have multiple band saw blades.

 

[Bruce Johnson]

I went to the Shop with Knowledgeable Staff, and sure enough someone knew a Dutch word for "spot drill". I hope he got it right. I bought these:

Those are not Spotting Drills, as we define them here in the US. We call those Center Drills; they are made for use in metal lathes, drilling the spots and cones in the ends of round parts to be supported by the tailstock Center.

However, Center Drills will work fine as Spotting Drills. Just make the Spot with the tip. Don't drill all the way in to the big cone.

 

[Bruce Johnson]

I also bought an automatic center punch, a hammer center punch and a drill press vise.
(I made up "hammer center punch".)

The vise has quite a bit of wear, it has the chrome plating falling off in places. I hope it served its previous owner well. By the way, I checked that it slides freely on my drill press table.

Looks good. Those are essential tools for Metalworking. That vise should be fine for your hardware projects. You'll probably want to make up a set of aluminum step jaws for it. If you flip it over, there are usually two bolts up inside the center that will adjust the clearance of the sliding jaw on the frame. Play around with them to get the jaw to slide smoothly with no wobble or slop.

 

[Bruce Johnson]

My plan right now is to make a front control cover plate from 2mm brass, for my SBO project. At first I decided not to cut this on the band saw, because of the SparkleWood effect, but I find it very tough to cut by hand.

So now I'm wondering whether to cut it on the band saw after all, and defy the SparkleWood problem. Or, of course, have multiple band saw blades.

The thing about sawing metal like brass is that you have to push down on the blade with much more force that you would on wood or plastic. Like 5 X the force. Do that, and it will cut surprisingly quickly.

Sawing it on the bandsaw is definitely better. And you also have to push the metal into the blade with 5 X the force.

You can avoid SparkleWood by cleaning the bandsaw thoroughly when you are done with the brass. Take the blade off, wipe the blade completely with a cloth. Use a bristle brush to clean the brass particles off of the rubber tires, and out of the blade guide assemblies. Vacuum out the housings. It's not that bad if you are only sawing metal occasionally.

 

[rickwrench]

You can avoid SparkleWood by cleaning the bandsaw thoroughly when you are done with the brass. Take the blade off...

SparkleWood... now that's a good band name.

Handling, coiling, uncoiling blades is the fun part. Learning to sharpen and silver/hard solder blades back together will save you a fortune.

Rick

 

[MovinTarget]

So my dad's friend was living in their house when he fell ill and passed. He had no contactable next of kin (my dad really tried!) So he's let me take a look and I found this set... dunno if its "quality" or should be for thread repair only...