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05-29-2006, 09:30 PM
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#1 |
Name: Pete City: Charlotte State: NC County: Mecklenburg Join Date: Jan 2006 Avg Visit Freq/Week
= 7.00 over 30 days |
Most of the mags use 3/4 plywood for jigs. I use MDF ('cause it's cheaper!). Am I missing something? What, if any, are the benefits of using ply over MDF?
pete |  
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05-29-2006, 09:53 PM
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#2 | | Moderator
Name: Ray City: Raleigh State: NC County: Wake Join Date: Mar 2006 Avg Visit Freq/Week
= 0.00 over 30 days |
Pete,
Both MDF and ply are strong and stable, which are important traits for jigs. MDF certainly mills up very nicely... maybe a bit better than plywood.
With MDF, I think you have to be a bit more careful with the fastener you choose. I think nails hold better in ply. The wrong screw or too much torque on a screw can tear up MDF more easily than it would plywood.
I think if you pay attention to how you fasten the pieces, either material makes for good jigs.
Ray
__________________
I cut that board twice and it's STILL too short.
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05-29-2006, 10:38 PM
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#3 | | Moderator
Advisory Panel
Name: Clay Lowman City: Willow Spring State: NC County: Wake Join Date: Oct 2005 Age: 36 Avg Visit Freq/Week
= 5.83 over 30 days |
MDF also makes one heck of a mess. (I use it for my jigs too, cause it's cheaper)
__________________
-Clay  | |
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05-29-2006, 10:46 PM
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#4 | | DQ
Name: Lorraine City: Littleton State: NC County: Warren Join Date: Dec 2005 Age: 60 Avg Visit Freq/Week
= 3.50 over 30 days |
Here is a hint for you. When you take your trash to the local trash dump look for scraps of plywood. You would be amazed at what someone will throw away. Just store it in a dry place and wait for the proper size jig to come along. Don't laugh, there is a lot of good plywood there. | |
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05-30-2006, 08:14 AM
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#5 |
Name: Pete City: Charlotte State: NC County: Mecklenburg Join Date: Jan 2006 Avg Visit Freq/Week
= 7.00 over 30 days |
::..With MDF, I think you have to be a bit more careful with the fastener you choose. .::
I just read an article on fastening MDF. Basically it said to use sheet metal screws rather than wood screws (straight not tapered). Drill the hole in the top piece for a loose fit and countersink both sides of the hole. Seems like a lot of trouble but it would be worth it for a good jig.
Yup, it does make a mess. I generally cut it in the driveway and use my leaf blower to "spread it around".
I haven't been to a dump in ages! Brings back memories. When I was in the service we used to have a few brews and go down to the local dump and shoot rats. Ah, the good ol' days 
pete | |
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05-30-2006, 02:27 PM
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#6 | | Asst. Webmaster
Senior Moderator
Name: DaveO City: Clayton State: NC County: Johnston Join Date: Aug 2005 Age: 38 Avg Visit Freq/Week
= 7.00 over 30 days |
I find that MDF is flatter and truer than most Plywood. As said before it's fastener holding capability is less. I'll often glue a hardwood strip to the MDF if I have to use any fasteners on or near the edge of it.
Dave 
__________________   Nothing left to do but smile, smile, smile
Honestly Honey, that will cost around $100 $150 $200, and I need a few more tools. 
Heard from a client..."If I had your tools and experience...I could do it myself" 
"Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind."
--Dr. Seuss
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05-30-2006, 02:43 PM
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#7 | | Webmaster
Advisory Panel
Name: Steve City: Apex State: NC County: Wake Join Date: Jul 2005 Age: 64 Avg Visit Freq/Week
= 7.00 over 30 days |
Becuase of the thundering chorus for my expert opinion, I'll add my 2 cents.
The biggest issue I have for MDF jigs is becuase of the way reacts to liquid spills. In my case, coffee. I have spilled coffee everywhere in my shop. And the one time I did use MDF, the coffee pretty much destroyed it. 
__________________
Steve Coles
"If you can't say something nice, at least make it funny"  | |
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05-30-2006, 02:49 PM
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#8 | | Asst. Webmaster
Senior Moderator
Name: DaveO City: Clayton State: NC County: Johnston Join Date: Aug 2005 Age: 38 Avg Visit Freq/Week
= 7.00 over 30 days |
Steve, that's why there should be no drinking in the workshop
If you give the MDF a good coat of poly or shellac you can avoid that problem also.
Dave
__________________ Nothing left to do but smile, smile, smile
Honestly Honey, that will cost around $100 $150 $200, and I need a few more tools.
Heard from a client..."If I had your tools and experience...I could do it myself"
"Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind."
--Dr. Seuss
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05-30-2006, 02:56 PM
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#9 | | Moderator
Name: Wayne City: Cary State: NC County: Wake Join Date: Dec 2005 Age: 61 Avg Visit Freq/Week
= 7.00 over 30 days |
Steve, that's why there should be no drinking in the workshop
If you give the MDF a good coat of poly or shellac you can avoid that problem also.
Dave  Not sure about that, DaveO. Steve likes his coffee pretty strong!!!!! 
Wayne
__________________ ..............found out many years ago that Elbow Grease doesn't come in a bottle!!!! | |
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05-30-2006, 03:20 PM
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#10 |
Name: Pete City: Charlotte State: NC County: Mecklenburg Join Date: Jan 2006 Avg Visit Freq/Week
= 7.00 over 30 days |
Steve - You must be tough on computer keyboards also  | |
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05-30-2006, 04:28 PM
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#11 |
Name: Joe City: Kernersville State: NC County: Forsyth Join Date: Sep 2005 Avg Visit Freq/Week
= 0.00 over 30 days |
I prefer plywood. The mess from MDF isn't worth the trouble for me. | |
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05-30-2006, 06:38 PM
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#12 | | Libraries Administrator
Name: Rob City: Hendersonville State: NC County: Henderson Join Date: Nov 2005 Age: 66 Avg Visit Freq/Week
= 7.00 over 30 days |
I've used both materials. But when I need a rock solid, gotta-be-flat surface, then I use 3/4" MDF or Baltic Birch. MDF takes a beautiful dado and if you use barbless t-nuts for any threaded knobs, it works great. Check out a few jig examples in my Photo Gallery.
Rob
__________________
Rob  Truths: There is no such thing as a 25 hour day, so why do I keep trying to cram so much into every day so it seems that way!   | |
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05-30-2006, 07:47 PM
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#13 |
Name: Pete City: Charlotte State: NC County: Mecklenburg Join Date: Jan 2006 Avg Visit Freq/Week
= 7.00 over 30 days |
OK - So it seems the down side to using MDF is:
1. It makes a mess
2. You have to take care joining it.
2. You can't spill coffee on it.
The up side is:
1. It's flat
2. It's less than half the price of 3/4 ply.
So.........Poor as I am I think I'll stick with the MDF.
pete | |
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05-31-2006, 01:42 PM
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#14 |
Name: John City: Raleigh State: NC County: Wake Join Date: Sep 2005 Avg Visit Freq/Week
= 5.37 over 30 days |
One other problem I've run into with MDF is it will absorb moisture over time and swell. I had some 3/4" mdf stored for some time and when I went to use it I found it was now 13/16" or better. Sealing with a shellac based based sealer will help greatly but any rabbits or other cuts may swell over time - probably not doing any good for the accuracy of your jig.
I usually figure on plywood for long term jigs and mdf for single use. | |
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05-31-2006, 03:11 PM
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#15 | | Webmaster
Advisory Panel
Name: Steve City: Apex State: NC County: Wake Join Date: Jul 2005 Age: 64 Avg Visit Freq/Week
= 7.00 over 30 days |
Originally Posted by Tekkadan Steve - You must be tough on computer keyboards also Yes on table tops, keyboards, shirts, rugs and on my marriage from the messes I cause.
__________________
Steve Coles
"If you can't say something nice, at least make it funny" | |
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