The Acoustic Guitar Forum

Go Back   The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Build and Repair

Reply
 
Thread Tools
  #1  
Old 07-26-2013, 10:23 PM
mustache79 mustache79 is offline
Registered User
 
Join Date: Jun 2012
Location: Earth
Posts: 1,198
Default Granite Surface Plates- making things flat

In a previous post it was recommended to maybe get a granite surface plate to check and make my own straight edges.

I saw this today and started thinking... http://www.woodcraft.com/PRODUCT/200...FSJlMgodtkgAng
__________________
I actually have a goatee. ..

Last edited by mustache79; 07-26-2013 at 10:29 PM.
Reply With Quote
  #2  
Old 07-27-2013, 01:30 AM
Viking Viking is offline
Registered User
 
Join Date: Mar 2013
Location: Colorado Springs, CO
Posts: 234
Default

I've got something very similar to that. Though mine is about 24" long. It's extremely handy. I use it all the time for a number of different purposes.

I got it at a used building supply store. Do you have anything like that where you live? If not, you could ask anyone in your area who installs granite counter tops if they have any cast offs, any pieces that are throw aways because of a cutting mistake. They are often plenty flat and cheep too. Cheeper than what you linked from woodcraft. At least, they are around here. I got mine for 6 bucks.
__________________
-- Nick
Reply With Quote
  #3  
Old 07-27-2013, 05:05 AM
Tom West Tom West is offline
Registered User
 
Join Date: Jan 2010
Location: Nova Scotia
Posts: 1,067
Default

Have no knowledge of the flatness of granite counter tops but am sure they are not in the same league with granite surface plates. That said, most likely they work super for most guitar work. Guitar measurements and tolerances are not very exact.
Tom
__________________
A person who has never made a mistake has never made anything
Reply With Quote
  #4  
Old 07-27-2013, 05:27 AM
fazool's Avatar
fazool fazool is offline
Charter Member
 
Join Date: Dec 2012
Location: Buffalo, NY
Posts: 16,559
Default

Granite surface blocks are extremely flat and typically used in Quality/Inspection departments of manufacturing companies where tolerances are measured in the 0.0001" range (tenths of thousandths).

Their flatness depends on the grade. See this link for more info.

Generally speaking, these are very expensive and overkill for woodworking where tolerances are measured in the .015" range (1/64").

If you can get one used they would be great.

A granite countertop or simple aluminum bar would suffice for precision woodworking
__________________
Fazool "The wand chooses the wizard, Mr. Potter"

000-15 / GC7 / GA3-12 / SB2-C / SB2-Cp / AVC-11MHx / AC-240
Reply With Quote
  #5  
Old 07-27-2013, 08:01 AM
clintj clintj is offline
Registered User
 
Join Date: Oct 2012
Location: Idaho Falls, ID
Posts: 4,267
Default

Just a random thought, but I lap my waterstones against each other to keep them flat. I wonder if you had two moderately flat countertops chunks and lapped them against each other if you would get two extremely flat surfaces.
__________________
"You don't have to be great to start, but you have to start to be great." -Zig Ziglar

Acoustics
2013 Guild F30 Standard
2012 Yamaha LL16
2007 Seagull S12
1991 Yairi DY 50

Electrics
Epiphone Les Paul Standard
Fender Am. Standard Telecaster
Gibson ES-335
Gibson Firebird
Reply With Quote
  #6  
Old 07-27-2013, 08:29 AM
nate clark nate clark is offline
Registered User
 
Join Date: Aug 2006
Posts: 142
Default

Quote:
Originally Posted by mustache79 View Post
In a previous post it was recommended to maybe get a granite surface plate to check and make my own straight edges.

I saw this today and started thinking... http://www.woodcraft.com/PRODUCT/200...FSJlMgodtkgAng
That will work great, buy it. My first granite slab was 8.5" x 11" " ish and I bought it from wood craft. It was very flat and worked fine albeit a bit short for my preferences. The one you linked to is a good dimension for repair work and tool maintenance.
Reply With Quote
  #7  
Old 07-27-2013, 11:20 AM
Tom West Tom West is offline
Registered User
 
Join Date: Jan 2010
Location: Nova Scotia
Posts: 1,067
Default

Quote:
Originally Posted by clintj View Post
Just a random thought, but I lap my waterstones against each other to keep them flat. I wonder if you had two moderately flat countertops chunks and lapped them against each other if you would get two extremely flat surfaces.
Absolutely not. You need three plates to lap and check against each other to make sure you get to a flat surface. Two plates can match each other, but one can be convex and one can be concave. The third is required to separate them.
Tom
__________________
A person who has never made a mistake has never made anything
Reply With Quote
  #8  
Old 07-27-2013, 12:27 PM
naccoachbob naccoachbob is offline
Registered User
 
Join Date: Jan 2010
Location: Nacogdoches, Tx
Posts: 666
Default

A couple years ago, I went to a shop that sold granite and marble, and asked to buy some of their stones that they couldn't use. I went away with two 2x2 1/2 foot pieces plus a couple of 6"x24" pieces as well. I gave half of it to Steve Kinnaird. The big piece I kept, I use to glue up top and back boards, to check side profiles, and for a lot of other work. The smaller piece I use to fret the fretboard. Since I don't have a shop, I do this on the patio. Makes a great steady surface.
As to exact degree of flatness, I'm not sure, but it's worked well enough for me. I think I spent about $50 total.
If I had it to do over again, I'd get it about 24"x20". That stuff is heavy. If you carry it around, be extremely careful or wear steel toed shoes. Don't ask how I know this.
Reply With Quote
  #9  
Old 07-27-2013, 12:47 PM
Quickstep192 Quickstep192 is offline
Charter Member
 
Join Date: Aug 2002
Posts: 1,656
Default

I have a marble threshold from the local tile store at a reasonable price. I've never measured the tolerance, but it seem pretty darn flat. I used it as a clamping caul to clamp a fingerboard on a banjo neck and got great results.
Reply With Quote
  #10  
Old 07-27-2013, 01:02 PM
leftybanjo leftybanjo is offline
Registered User
 
Join Date: Jan 2011
Location: boerne, tx
Posts: 809
Default

You can go to a commercial glass company and get a piece of "float glass", I use a 1/2" thick that was left over from a table top. Float glass is perfectly flat and not too heavy to carry. Wet it and wet or dry sandpaper stick well for sharpening tools.
Reply With Quote
  #11  
Old 07-27-2013, 01:22 PM
clintj clintj is offline
Registered User
 
Join Date: Oct 2012
Location: Idaho Falls, ID
Posts: 4,267
Default

Quote:
Originally Posted by Tom West View Post
Absolutely not. You need three plates to lap and check against each other to make sure you get to a flat surface. Two plates can match each other, but one can be convex and one can be concave. The third is required to separate them.
Tom
Ah, that makes sense. A coworker who is big into astronomy also pointed that out, he has hand ground telescope mirrors using two huge glass blanks against each other with fine abrasive. Learned something new today.
__________________
"You don't have to be great to start, but you have to start to be great." -Zig Ziglar

Acoustics
2013 Guild F30 Standard
2012 Yamaha LL16
2007 Seagull S12
1991 Yairi DY 50

Electrics
Epiphone Les Paul Standard
Fender Am. Standard Telecaster
Gibson ES-335
Gibson Firebird
Reply With Quote
Reply

  The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Build and Repair

Thread Tools





All times are GMT -6. The time now is 06:44 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright ©2000 - 2022, The Acoustic Guitar Forum
vB Ad Management by =RedTyger=