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Working with a machinist
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=3878		 Page 1 of 1
Author:  Brock Poling [ Wed Nov 23, 2005 6:26 am ]
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I am considering streamlining my neck construction by developing some jigs and templates. Rather than making these out of wood I have been considering hiring a machinst to help me with constructing them out of aluminum. My suspicion is that in the long run they will be much nicer and hold up a lot better.

However, I have no idea what the process is for working with a machinist. What do they expect in terms of drawings (CAD, hand sketch, measurements, ???). And how accurate can you realistically expect the process to be?

A while back, I had a company help me create some solid body routing templates off of a set of commercial plans, and while they were close enough to be used, they were not entirely accurate. Certainly not accurate enough for neck work.

Sorry to be a dufus about this stuff, but I spend my days working on marketing... I figure it is better to ask up front than learn my lesson the hard way.
Author:  Bobc [ Wed Nov 23, 2005 6:37 am ]
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Brock you might start with John Hall. He is a machinist by trade and could probably answer most of your questions.
Author:  Jim Watts [ Wed Nov 23, 2005 6:59 am ]
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Brock,
Different shops are different. A good had sketch will work for a lot of shops, but not all. The important thing is make your tolerances really clear. If something needs to be within a few thousands of an inch make that clear to the shop. Use a tolerance block to communicate your wishes. 3 place decimals have a tighter tolerance than two place decimals, which have a tighter tolerance than one place decimals.
No need to go four places, but set your three tolerance to what ever precision you want. .005 is easy for a machinist to hold, while .001 or better will cost you extra $$$.

A typical tolerance block might look something like this.
X.X = +/- 0.1
x.xx = +/- .030
x.xxx = +/- .005
Put this at the bottom of your drawing and then add any tolerances to specific dimensions that might differ from the standard spelled out in the tolerance block.

Also think about how you dimension your sketch, where the dimensions are coming from, for example maybe it should be dimensioned from the 14th fret location, nut or some other significant location. this helps keep everything in the right loaction and prevents tolerance stack up errors.
I've done a lot of this and would be happy to review your sketch for clairity if you'd like.

Author:  Michael Dale Payne [ Wed Nov 23, 2005 7:44 am ]
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Machine standard tolerance includes a flatness concentic, and parallel tolerance. I deal with this every day. Most Machinist will help with this as you work with them.

I am going to disagree with Jim on his tolerances, though he is right that they may vary from shop to shop. This is the industrial machining tolerances most commonly used for persision machining
Fractional dim= + or - 1/16"
.xx = + or - .045
.xxx = + or - .010
.xxxx= + or - .0010

If you have surfaces that need to be square, flush, flat, concentric, parallel and so on ther are special syembles used to indicate to the machinist the toerance.

if you need help on drawings let me know
Author:  Don Williams [ Wed Nov 23, 2005 7:50 am ]
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Consider one of the folks here who have a cnc. They could easily make aluminum jigs with it. I think if I had a cnc, that would be as big a part of what I use it for as making guitar parts. At least at first. But be aware that aluminum plate is very expensive stuff. Although the jigs made from it will last a lifetime, the initial expense outlay will be substantially more than using other materials. A friend recently turned me on to using tempered hardboard, that thin stuff you can get cheaply at home depot, with one shiny side and one rough side. He runs the rough side lightly through the thickness sander, then uses polyurethane glue to laminate two pieces into a 1/4" sandwich. Makes Great jig material. You can build it up to 3/8" or 1/3" if you prefer. Much cheaper than aluminum, but works great. You would have to use threaded inserts in it though for certain things, whereas you can tap aluminum. Some folks even add steel inserts into aluminum jigs because threads cut in aluminum can strip out.
Author:  npalen [ Wed Nov 23, 2005 8:14 am ]
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What everyone above is saying plus it depends a lot on the skill of the particular machinist and/or shop. Some guys can take your need for a tool or fixture and translate it into a finished tool with no formal drawing or even a sketch. Knowing what the end result needs to be may allow him/her to take shortcuts to save cost provided they understand precisely the desired end result.
Nelson
Author:  letseatpaste [ Wed Nov 23, 2005 8:41 am ]
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If the machine shop you're working with has a waterjet, you can give them an electronic copy of a .dxf file. That works out great for 2d-ish parts with different shaped profiles, especially for odd curves and things like that. And it's not as labor intensive so it's typically costs less. It'd be the ideal thing for routing templates.
Author:  Brock Poling [ Wed Nov 23, 2005 9:17 am ]
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Thanks. These are great comments.

Author:  Don Williams [ Wed Nov 23, 2005 10:05 am ]
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Jon is sure right about that. They can do amazing things with a waterjet these days. I get glued to watching American Chopper on tv and they frequently make some really great stuff with one.
Author:  Keith M [ Wed Nov 23, 2005 10:36 am ]
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Brock here is a cool site which may be worth looking     
into, free CAD and quotes.     

http://www.emachineshop.com/
Author:  ctholden [ Wed Nov 23, 2005 10:40 am ]
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I checked into having some aluminum parts made for my jigs when I first started out, but the cost was my deterrent.

Craig
Author:  Brock Poling [ Wed Nov 23, 2005 12:16 pm ]
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Hopefully these will be a lifetime investment.

In truth, if this idea works out well, I may need one for each major body style I build. But.... I think the time savings will be substantial -- certainly enough to justify the cost (within reason).

I am sure it is cheaper than a CNC machine.   
Author:  tippie53 [ Wed Nov 23, 2005 4:02 pm ]
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     Making jigs is a trade allmost to itself. A good machineshop will have the tools and experience. Water jets are great things but often these are for profiling and depending on the material you sometime have some squaring issues.
      milling cnc may be the best for this as X Y and X axis is controlled , in water jets it is 2 dimensions X and Y. Also aluminium comes in many alloys. I like fortal as it is a good machining material. Alum is okay but your finish can sometimes be a little rough. Fortal is also more wear resistant. Alum is soft and will dent easier.
      Most Machineshops will use and translate most files. I can tell you that most shops will have set up fees that can get very expensive. Here in this area are 150 on up.
John
Author:  Shawn [ Wed Nov 23, 2005 7:52 pm ]
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I agree with John...Fortal is a great way to go...I have built alot with it and is better than aluminum. If you come up with a jig that has mass appeal it would be a good thing to sell to members...if you take a pre-order count you might be able to negotiate a better price with the machinist as it will be one setup charge and the the time and materials for the run.

The Luthier who was the most into having all of his jigs done in metal was Art Overholtzer...He had alot of his jigs and forms cast and then machined. If you check out his book on classical construction it has alot of great vintage photos of his jigs.
Author:  Brock Poling [ Wed Nov 23, 2005 11:51 pm ]
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This is one of those things that has a lot of personal preference built in. But it might be something that would have a wide interest.
Author:  tippie53 [ Thu Nov 24, 2005 12:19 am ]
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Hi Brock
     can you send me a scetch? I don't know is I have the equipment but there are 4 shops in my area
john
Author:  johno [ Thu Nov 24, 2005 1:26 am ]
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Hey Brock,

In a former life I was a toolmaker and worked in a little R&D shop for a big manufacturing co. Some of the best things we came up with were when someone would come in with just an idea of what they were trying to do. We would brainstorm the project together and then we (in the shop) would build it. This worked really well. I kinda like to think this was a special group of talented toolmakers, moldmakers and modelmakers. We took offense to being called machinists. The machinists in our company only worked to blueprints but our group was into the R & D.

If you can find a small shop that has someone that work with you like this, you may find that you may even come up with a different approach to your jigs and fixtures. I saw one guy's shop where he had lots of aluminum fixtures made up in just this fashion. It can work ... but it could be a sizeable investment too.

All that said, if you have an exact fixture in mind with all the acceptable tolerences, you could just deliver the print and have that made up at a "shop rate." Not as much fun, but probably a bit cheaper.

Have a great one.

John O
Author:  John Kinnaird [ Fri Nov 25, 2005 8:54 am ]
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I would love to see what you have in mind. I am trying to streamline neck construction myself. That is what I consider the coolie work of the guitar making process. I would like to farm that out if I could afford it. But, barring that I would love to see any ideas for streamlining the process.

I used to consider carving necks with chisel and drawknife and rasp etc. etc. the romantic part of the process. No longer. Done that and want to concentrate on something else.
Author:  Brock Poling [ Fri Nov 25, 2005 9:21 am ]
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It is no big secret, but I am still refining my thoughts...

I will tell you that a post on MIMF by Robin Griffin is the inspiration behind this.

First he has an aluminum template of the fingerboard that has pilot holes drilled in it and a slot for the truss rod. The template could either pin or stick to the neck for proper truss rod location. Additionally drilling the pilot holes could help with registration of the fingerboard (which this same template would help locate those pilot holes as well.

I was planning on leaving the fingerboard template a little long behind the nut. ~.220" or so so I could mount the nut on the flat part of the neck before the angle of the headstock.

Then I have been thinking about adding slots for carbon fiber, more registration pins to help locate everthing easily on the raw neck stock etc.

And this could obviously get into creating custom router bushings as well as the actual templates themselves.

So that takes care of the fingerboard and neck blank.

Then, to profile the neck, I was going to have a chassis made that cut the neck to the exact perfect taper to match the fingerboard.

Then, if I wanted to take it a step further this jig could also be used with some custom made shaper cutters that could put a rough profile on the neck. (I would still carve the heel by hand.)

Standard headstocks are pretty straight forward for me... but one thing I was thinking about doing for these is creating a template that had registration pins in it that allows me to create the headplate and locate it perfectly. (Now I just glue it on first and route the entire thing...) By doing it separately I could sand the perfect angle on the head plate at the nut so fitting a nut would be a much faster operation. Everything would be square and perfect with very little fuss.

I suppose these jigs could be made for mass consumption, but obviously every fingerboard you do reqires an entirely new set of jigs (which could be a hassle... not to mention expensive).

The goal of this is to 1) increase productivity. 2) Increase consistancy. Right now It takes me about 5 full evenings to make a neck start to finish (bound fb, bound head stock, back strapped, etc.). I certainly don't mind putting the time into it. But having the tools to make this a more efficient process are very tempting.
Author:  John Kinnaird [ Fri Nov 25, 2005 12:51 pm ]
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sounds good to me.
One thing I have been doing of late is gluing the fingerboard onto the neck before shaping the neck, and then using the fingerboard as a router guide to make the neck taper fit the fingerboard. I have a bearing on the cutter that follows the edge of the fingerboard and that makes one less template to make.

Thanks for the info.

John
Author:  Steve Saville [ Sun Nov 27, 2005 6:35 am ]
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Brock,
I am a mechanical engineer. I work with drawings and machinists all the time. Can you email me what you have in mind and I'll get back to you. I can make drawings (Autocad) very fast. The better the drawing, the better the fixture. I work with tolerances in the ± .0002" and I have a good idea on what materials you should use and what processes and finish specs to call out. If I do it, I won't charge you anything except perhaps the right to make my own set of tooling from the drawings. Perhaps I could find a good shop and you could make and sell them.
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