Super-lightweight P bass build

[Matt Liebenau]

Sympathy like but, yes, even in soft metal I try to use at least a little cutting oil when drilling or tapping. If I for some reason I don’t have cutting oil even a couple of drops of 3 in 1 oil. I don’t know what that translates to in UK available products.

 

[Flying B]

Sympathy like but, yes, even in soft metal I try to use at least a little cutting oil when drilling or tapping. If I for some reason I don’t have cutting oil even a couple of drops of 3 in 1 oil. I don’t know what that translates to in UK available products.

Just found this in the cupboard under the drill press.

 

[T_Bone_TL]

Did it break as it came out (or was just about to come out) the backside of the bar?

That can be a problem with bits ground for steel (the default twist drill grind) used in brass/bronze/aluminum. The cutting angle is a bit too aggressive for the softer materials and the bit will grab. While one can get away with using unmodified bits, in a metalworking shop it's common to sharpen a set for brass or other soft metal work with a less acute cutting edge so the bit does not grab. Don't think I've ever seen factory bits made that way, though they may exist - it's a shop modification as far as I know (often on a bit being retired from steel work.)

Copper (I used to work in a high voltage plasma lab long ago) is even worse for grabbing drills.

Hopefully this link is not geofenced and you can see it. I found many pages with pictures that would not load as they were out of date in trying to find a visual guide for you.

Drilling Brass: the easy and safe way ⋆ handycrowd.com

I remember my dad showing me this drilling brass trick more than 30 years ago. And who better to show you, other than the guys on the Home Model Engine Machinist forum because they really know their stuff when it comes to tricky machining jobs. Here is what Deanofid had to say about an easy way...

handycrowd.com

Likewise, you want to "peck" as you drill, which basically means drill a little, pull the drill out of the hole, drill a little more to keep the chips cleared out.

 

[Flying B]

Did it break as it came out (or was just about to come out) the backside of the bar?

That can be a problem with bits ground for steel used in brass/bronze/aluminum. The cutting angle is a bit too aggressive for the softer materials and the bit will grab. While one can get away with using unmodified bits, in a metalworking shop it's common to sharpen a set for brass or other soft metal work with a less acute cutting edge so the bit does not grab. Don't think I've ever seen factory bits made that way, though they may exist - it's a shop modification as far as I know (often on a bit being retired from steel work.)

Yeah it broke through the bottom then grabbed and broke. I think the real problem was there's no vise so i was just holding the brass between two bits of MDF and it wobbled a bit. Need to come up with something better that I can clamp down to the table.

 

[T_Bone_TL]

Yeah it broke through the bottom then grabbed and broke.

Voice of experience - that is the real problem, or at least most of it. That's why I knew to ask that question.

It will do that when held in an utterly proper metalworking drill press vise.

You can use a few more clamps to clamp the MDF-Brass-MDF sandwich down to the table, but 30 seconds altering the bit geometry (which won't markedly hurt it for woodwork) will make a major difference.

 

[Matt Liebenau]

Did it break as it came out (or was just about to come out) the backside of the bar?

That can be a problem with bits ground for steel (the default twist drill grind) used in brass/bronze/aluminum. The cutting angle is a bit too aggressive for the softer materials and the bit will grab. While one can get away with using unmodified bits, in a metalworking shop it's common to sharpen a set for brass or other soft metal work with a less acute cutting edge so the bit does not grab. Don't think I've ever seen factory bits made that way, though they may exist - it's a shop modification as far as I know (often on a bit being retired from steel work.)

Copper (I used to work in a high voltage plasma lab long ago) is even worse for grabbing drills.

Hopefully this link is not geofenced and you can see it. I found many pages with pictures that would not load as they were out of date in trying to find a visual guide for you.

Drilling Brass: the easy and safe way ⋆ handycrowd.com

I remember my dad showing me this drilling brass trick more than 30 years ago. And who better to show you, other than the guys on the Home Model Engine Machinist forum because they really know their stuff when it comes to tricky machining jobs. Here is what Deanofid had to say about an easy way...

handycrowd.com

Likewise, you want to "peck" as you drill, which basically means drill a little, pull the drill out of the hole, drill a little more to keep the chips cleared out.

Interesting. I was not aware of that. I’ll read through the link.

 

[Bruce Johnson]

Started work on the Bruce bars, then this happened,
View attachment 7125412
It was a cheap set, but it broke very easily. Am I supposed to be using some cutting fluid or something? I'll need to wait for a new 4.2mm still bit to arrive now.

Ugh. Yep, I've done that. Yes, I almost always use Tapping Fluid when tapping all metals. Tapping brass is particularly annoying because it tends to spring back and squeeze the tap, increasing the friction. Without oil, it'll start making clicking and scraping sounds and getting harder to turn. Then you apply a little too much torque and it snaps.

Tapping Fluid is a special variant of Cutting Oil, made for tapping. It's thicker and stickier than normal oil, so it stays on the tap and feeds into the threads as they are being cut. Regular Cutting Oil will work, but not as well. Normal lubricating oil will also work, but not as well.

I see that you have the tap in your drill press chuck, which is good, but were you turning it by hand? Or were you trying to power tap it?

I go over types of taps and how to use them here on this thread:

https://www.talkbass.com/threads/ma...ware-for-basses.1606725/page-15#post-27624381

And:

https://www.talkbass.com/threads/ma...ware-for-basses.1606725/page-17#post-27667144

 

[Flying B]

Ugh. Yep, I've done that. Yes, I almost always use Tapping Fluid when tapping all metals. Tapping brass is particularly annoying because it tends to spring back and squeeze the tap, increasing the friction. Without oil, it'll start making clicking and scraping sounds and getting harder to turn. Then you apply a little too much torque and it snaps.

Tapping Fluid is a special variant of Cutting Oil, made for tapping. It's thicker and stickier than normal oil, so it stays on the tap and feeds into the threads as they are being cut. Regular Cutting Oil will work, but not as well. Normal lubricating oil will also work, but not as well.

I see that you have the tap in your drill press chuck, which is good, but were you turning it by hand? Or were you trying to power tap it?

I go over types of taps and how to use them here on this thread:

https://www.talkbass.com/threads/ma...ware-for-basses.1606725/page-15#post-27624381

And:

https://www.talkbass.com/threads/ma...ware-for-basses.1606725/page-17#post-27667144

Bruce that was the drill bit that snapped, not the tap. I went on to tap the two holes I managed to drill and it went without a hitch (using the cutting fluid).
I wonder how critical is the 0.2mm? Could I get away with a 4mm bit? Or 4.5?

 

[Flying B]

Bruce bars are coming along, the weight relief holes are all over the shop, but the bolt holes are in the right place. It's surprisingly hard to drill a straight line of holes in metal!

 

[Flying B]

I started work on the template today. I first pieced this together with ca glue.

Then transferred that to my neck template. I just need to round the corners of the bars

 

[Flying B]

 

[tidbits]

Wow, nice work with the templates and the transfers.

I need to do a similar bit of surgery to salvage a neck and I hadn’t puzzled out how to achieve it yet

Apparently it’s going to look awfully similar to this process here.

 

[Flying B]

Bars routed into neck.

I chucked a bolt in my drill and ran it against the belt sander, I can use this to transfer the hole locations to the body, once I've drilled through the rest of the neck.

 

[Flying B]

Finally got the neck fitted to the body after what feels like an age.

The top two bolts are not quite in line with each other, and the neck pocket edge isn't quite matching the neck, but waddayagunnado.

At some point you have to decide "good enough" and move on. Can get on with attaching the fretboard next, although for reasons I can't actually remember I think I'm going to radius it first.

 

[T_Bone_TL]

the neck pocket edge isn't quite matching the neck, but waddayagunnado.

File it when you shape the neck heel, in this case, presumably.

 

[Beej]

The top two bolts are not quite in line with each other, and the neck pocket edge isn't quite matching the neck, but waddayagunnado.

And add it to your 'big book of lutherie' for the next instrument.

That top is hawt stuff!

 

[Flying B]

And add it to your 'big book of lutherie' for the next instrument.

That top is hawt stuff!

Joking aside, i really need to start keeping notes on this stuff so I don't keep making the same mistakes over and over again

 

[Beej]

Joking aside, i really need to start keeping notes on this stuff so I don't keep making the same mistakes over and over again

I literally have a big "book" of lutherie that has developed via this process. Though it's more of an electronic file folder system with hundreds of pics and a few documents to track details, pitfalls, methods and facts. I would have re-made a hundred mistakes without it.

 

[Flying B]

I got the fretboard radiused today. I used this cutter in the router table, you can just see the edge of the board taped to the "fixture" - just a square block of wood.

I just made multiple passes, flipping it each time and raising the cutter slightly until I reached the centre line.
As you can see I'll need to recut the fret slots a little. It's looking a bit thin at the edges but it's still oversized at this stage.

 

[TerribleTim68]

I've looked at those router bits, but man they freak me out. Might help if I had a real router table, not a benchtop stamped sheet metal wanna-be thing. But still....