I'm making a batch of keeper bars next weekend

[Dave Kerr]

50 * .001 = .050" per turn
4 turns = .200", 6 marks back from 4 full turns is .194"

8 turns = .400", 12 marks back from that is .388"

[corduroyew]

I almost forgot. I got the detailed spec sheet for my steel.

C .15
Si .166
Mn .811
P .007
S .012

I've posted it before but here is your standard variance for 1018

C .15-.20
Si .15-.35
Mn .60-.90
p .04 max
S .05 max


I've tried a couple of the new keepers and they sounds exactly like my last batch did. They have a nice balance that is great for the neck or bridge. They’ve got that goldilocks thing going on. Not too bright, not too boomy… these are just right. That’s what I think of them. I think they are much better than the punched kit keepers as far as tone and because mine aren't deformed from punching, they are easier to fit into place. I’m sure that I'm a bit biased with my opinion but the price is low and so is the shipping cost so you can always get a few now and then get more later if you like them.

[Possum]

thanks.....

after I wrote that, I manged to figure out the same thing by myself, wow. Maybe I'm not so dumb after all :-) This will be cool, using a steel drill hole guide on a mill is a pain in the butt and really slow and not very accurate, not recommended....

[corduroyew]

Thought I'd give you guys one more pic. Here is a keeper mounted onto a bobbin. Notice the very snug fit around the poles.

Here is one of mine
http://www.rockmonkeyguitars.com/images/keepers6.jpg

[Joe Gwinn]

Uh, I'm a little bit heavy right brainer here. The hole centers I need to drill are 0.19375" apart , that part I could figure out. What I'm confused about is my mill indicators on the table are 0.001" per small mark. There are 50 marks per turn. How many turns do I need to do and how many marks after that to hit this measurement? Same thing I need to know for the skip in the middle where the holes are 0.3875" apart. Any math whiz types here? Embarrassed thanks.....

First, some preliminaries:

49.2 mm over six poles is 49.2/5= 9.84 mm between poles.

9.84 mm is 9.84/25.4= 0.3874" between holes.


Second, it's 0.050" per turn, or 20 turns per inch. That seems plausible, being a standard thread (as in 1/4-20) so we will assume that it is correct in the following computation:

0.19375/0.050= 3.875 turns. So, go 3 turns plus (0.050)(0.875)= 0.04375= 0.044" on the dial.

For the 0.3874 dimension, it's 0.3874/0.050= 7.7480, or 7 turns plus (0.050)(0.748)= 0.0374= 0.037".


Beware error accumulation. Compute the exact location of each hole, and then convert to added turns and offsets in thousandths. A spreadsheet is very useful here, to avoid errors. Otherwise, the last hole will be way off.

[Possum]

...........

I didn't use milimeters, I used 1 15/16" and my mill is in inches not milimeters. I haven't done one of these yet, what is the best way to avoid error accumulation, I was going to drill the first hole then space it .19375" (well as close as I can using the marks) and do the same for the next hole. BTW there are 10 holes so the spacing is based on there being 11 holes, the middle hole isn't drilled so there's a blank space where that hole would be. So there are 10 spaces between holes so I did the math for 10 spacings or 10 jumps. Make sense? I may look into getting a digital readout for this thing at some point to make things simpler if I keep using it in production stuff....

[Joe Gwinn]

I didn't use millimeters, I used 1-15/16" and my mill is in inches not millimeters. I haven't done one of these yet.

If the spec is in millimeters, convert it to inches by dividing by 25.4, but keep lots of digits. Don't try to round it off to the nearest 16th of an inch.

What is the best way to avoid error accumulation? I was going to drill the first hole then space it 0.19375" (well as close as I can using the marks) and do the same for the next hole.

Generate the locations mathematically with full precision, and round only after generating all the full-accuracy hole locations.

BTW there are 10 holes so the spacing is based on there being 11 holes, the middle hole isn't drilled so there's a blank space where that hole would be. So there are 10 spaces between holes so I did the math for 10 spacings or 10 jumps. Make sense?

So, it's really 11 hole positions, but with one missing hole? If so, it's 10 spaces in 1-15/16 inches, so the spacing is 1.9375/10= 0.19375", and the hole locations are 0, 0.19375, 0.3875, 0.58125, and so on. Round these to the nearest thousandth of an inch: 0, 0.194, 0.388, 0.581, and so on.

I may look into getting a digital readout for this thing at some point to make things simpler if I keep using it in production stuff....

DROs are very useful, and speed things up greatly.

[David King]

CNC is very useful and speeds things up even more..

[corduroyew]

There are still a handful of you still waiting for the keeper bars. The parts to my bandsaw are still on backorder so I'm still waiting for them to come in. If any of you feel it's taking too long (haven’t had any complaints yet but wanted to say something before any came up) then I will happily refund your money. Otherwise, I'll get them made as soon as my bandsaw parts get here.

Sorry for the delay

[Sam Lee Guy]

Hi,
would like to try a few of your keeper bars. Standard PAF spacing, against common belief is 49.4mm. Don't know why, it just is. Can you make them this spacing?

[corduroyew]

I can but it'll have to wait until I've got the parts for the bandsaw in. They were supposed to be here a week and a half ago. Every time I call them they say "they should be in tomorrow" and then it never happens.