Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

What type of plywood?

17402 views
74 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    December 2016
  • 168 posts
Posted by speedybee on Sunday, January 29, 2017 1:59 AM

hon30critter

How would you suggest attaching pieces at a 90 degree joint without screwing into the end grain of one of the pieces?

It depends on the situation, but I expect you're thinking of how the crossbeams rest on the vertical supports (legs).

The most primitive option is to simply glue+screw their faces together at a right angle so that they form an L shape. Obviously this would offset the crossbeam to the side and so there'd be unfortunate torquing forces on the wood. But considering the relatively light load that is a model train layout I don't think it would even matter... it's not like you're parking a Winnebago on this.

A stronger and more symmetrical solution would have the crossbeam sit on the top of the leg, with their long widths aligned the same way, if that description makes sense. Basically, if viewed from the side, it looks like an upside down "L", with both the crossbeam and the leg showing their 3" or 4" sides. Then on each side of the joint overlap it with short pieces of 1x3 or 1x4, using screw+glue joints.

Face-to-face screw+glue joints of any decent surface area are basically unbreakable... the wood beams themselves will break before the joint.

Another already mentioned method is the corner blocks. Not as strong as the above method IMO when you're attaching a supporting beam to a leg, because the supporting beam has its long side vertical, as in roof rafters.

Re: small pieces of wood splitting when screwed, yes predrilling should take care of that.

But when still concerned about splitting, after you've predrilled your pilot hole, you can also go in very very shallowly with a big drill bit. All you want is the tapered triangular dent in the wood, because wood screws have the same triangular shaped head that forces the wood to split apart as it goes in.

And when really really concerned about splitting, I will also use two of the classic Irwin bar clamps, one on each end of the piece, so that it cannot split. Once the glue has set a bit, the clamps can come off.

I hope this post makes sense... It's 3am.

edit: as was just mentioned, stay away from the likes of home depot if you need decent lumber. I don't know about any lumber supplies in Bradford, as it's not my stomping ground, but if you ever happen to be up in Collingwood, I've never been disappointed with Bill Brown's.

  • Member since
    October 2005
  • 1,047 posts
Posted by betamax on Sunday, January 29, 2017 1:59 AM

I built a small 4X4 test structure using 3.5" wide 3/4 plywood and fastened the thing together with pocket screws.  It went together well and with a little bracing would be dimensionally stable.

When layout constuction commences I plan to use Baltic Birch plywood for the structure, as it is a lot better for pocket screws.  Googling around for those kit based layout systems revealed that is the material they often use.  The advantage to BB plywood is it has no voids.  Regular run of the mill plywood often has another species used as the core, and since it isn't seen, often has voids.  Voids don't hold screws.

To rip the plywood I plan to build a cutting table out of two sheets of particle board and use guides to get the right sizes.

Dollar for dollar, plywood is cheaper and more predictable than dimensional lumber.

Do stay away from the big box retailers, their wood isn't that great, and their customers do even more harm when picking though it. Speciality wood suppliers will often have Baltic Birch. 

  • Member since
    July 2006
  • From: Bradford, Ontario
  • 15,797 posts
Posted by hon30critter on Sunday, January 29, 2017 1:22 AM

7j43k
I've worked construction most of my life.  If that gets any credibility here.

Ed:

Your advice is definitely creditable. Thanks for sharing it.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

  • Member since
    July 2006
  • From: Bradford, Ontario
  • 15,797 posts
Posted by hon30critter on Sunday, January 29, 2017 1:08 AM

UNCLEBUTCH
From my experence, I would never trust screw into end grain on plywood, cornor blocks are better,if you must use ply.

UNCLEBUTCH:

What would you use for corner blocks? The suggestion was made to use 2x2s but I'd be concerned about them splitting since they would be less than 4" long. I guess if I pre-drill them that would not be an issue?

FWIW, using plywood is not a 'must' but I find the stability factor to be very attractive.

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

  • Member since
    July 2006
  • From: Bradford, Ontario
  • 15,797 posts
Posted by hon30critter on Sunday, January 29, 2017 1:04 AM

Hi Michael:

How did you do your 90 degree joints?

Thanks

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

  • Member since
    April 2012
  • From: Huron, SD
  • 1,016 posts
Posted by Bayfield Transfer Railway on Sunday, January 29, 2017 12:58 AM

1) Buy the best cabinet grade hardwood plywood you can, the more plies the better.

2) If you price it out you will find that even the most expensive plywood is WAY cheaper than individual 1 x 4s.  Do the arithmetic yourself.  The plywood will be straight and will not warp.  I used both plywood and pine 1 x 4s on my last layout.  The right answer is plywood.  Period.

 

Disclaimer:  This post may contain humor, sarcasm, and/or flatulence.

Michael Mornard

Bringing the North Woods to South Dakota!

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Sunday, January 29, 2017 12:26 AM

hon30critter

 

 
speedybee
IMO it'd be best not to screw into the endgrain of either, and I don't see why you'd really need to?

 

How would you suggest attaching pieces at a 90 degree joint without screwing into the end grain of one of the pieces? I could use corner brackets but that will get real expensive real fast.

Dave

 

You use corner blocks.  Typically 2 x 2's.  See earlier comment by other poster.

There are subtleties beyond this discussion.  But that's about it.

 

Ed

  • Member since
    July 2006
  • From: Bradford, Ontario
  • 15,797 posts
Posted by hon30critter on Sunday, January 29, 2017 12:18 AM

speedybee
IMO it'd be best not to screw into the endgrain of either, and I don't see why you'd really need to?

How would you suggest attaching pieces at a 90 degree joint without screwing into the end grain of one of the pieces?

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Saturday, January 28, 2017 11:53 PM

hon30critter

 

One of the reasons that I am considering plywood is that our model railroad club just happens to be in the back of a cabinetry shop. I haven't approached the owner yet but I'm hoping he could give me a reasonable price on the plywood and the cutting. When I talk to him I want to have at least a basic understanding of what I should be looking at. I have a radial arm saw but ripping 4x8 sheets on it is a pain, and my back won't allow me to handle 3/4 x 4 x 8 sheets anyhowAngry

Thanks,

Dave

 

You wrote this while I was writing.  Just do what he says.  The guy's an expert.  If you think he's going to screw you over, then don't do it.  If he's not, trust him.  That simple.

He probably knows more about how to solve your problems than all of us, here.  Including me.  Oh.  Did I say?  I've worked construction most of my life.  Like 40 years.  What would I know?

 

Ed

  • Member since
    November 2015
  • 723 posts
Posted by UNCLEBUTCH on Saturday, January 28, 2017 11:52 PM

IMHO, you don't need cabinet grade,A/b would work as well, good side out.

From my experence, I would never trust screw into end grain on plywood, cornor blocks are better,if you must use ply.

As others said I vote for 1x4s. If your picky  when you buy, use them up in a reasonable amout of time,don't leave em lay around too long. Once you have em screwed,nailed and/or glued they will stay where you put them

Don't be scare off by knots, if there small and tight, won't hurt anything.

  • Member since
    May 2004
  • 7,500 posts
Posted by 7j43k on Saturday, January 28, 2017 11:46 PM

3/4" ply is usually 7 ply.  You can pay more and get better, but I don't think it's worth it.

I agree that ripping down plywood to make planks is a real pain--just buy planks.

But them we run into quality problems.  If you use plywood, the defects average out.  If you have a knot in a 1 x 4, you REALLY have a knot.

I buy, on occasion, clear kiln dried fir.  Did you know it's REALLY expensive?  Especially if it's quarter sawn.  It is beautiful sweet wood.  EXPENSIVE.  And stable.  And strong.  And EXPENSIVE.

You will probably be happier with 3/4 ply ripped.  Really.

While there are some really neat plywoods that some of my buds use, I'm real happy with what is usually called shop grade.  It's AC interior.  Maybe AD.

I've worked construction most of my life.  If that gets any credibility here.

 

Ed

 

  • Member since
    December 2016
  • 168 posts
Posted by speedybee on Saturday, January 28, 2017 11:42 PM

I see you replied while I was typing my reply Smile re: the screwing into end grain, I suspect ply would less terrible at holding screws into endgrain than lumber, but IMO it'd be best not to screw into the endgrain of either, and I don't see why you'd really need to?

  • Member since
    December 2016
  • 168 posts
Posted by speedybee on Saturday, January 28, 2017 11:28 PM

I second the suggestion of good old fashioned 1x4s, or even 1x3s for that matter. Solid wood is stronger than ply, probably cheaper, and much easier to build with than having to rip 4x8 sheets of plywood dozens of times. Wrestling a 4x8 sheet into a table saw is not fun!

  • Member since
    July 2006
  • From: Bradford, Ontario
  • 15,797 posts
Posted by hon30critter on Saturday, January 28, 2017 11:26 PM

Hi Mike:

I'm pretty sure the grading is the same on both sides of the border. The industry specs for the Canadian stuff are in metric units but I think the classification of the makeup of the plywood is the same.

I'm looking at something with more than five plies. I think it is referred to as cabinet grade or furniture grade but I want to hear others thoughts on it before I spend the money. I believe that the higher grades have better screw holding ability when the screws are are going into the end grain. Somebody correct me on that if I'm wrong please. I do plan on pre-drilling the holes regardless of the material.

I am also going to price 1x4 clear lumber for comparison. I'd love to do the benchwork in poplar but that would definitely be expensive. We have a trim manufacturer close by who sells dimensional poplar wholesale so I will look at that too.

One of the reasons that I am considering plywood is that our model railroad club just happens to be in the back of a cabinetry shop. I haven't approached the owner yet but I'm hoping he could give me a reasonable price on the plywood and the cutting. When I talk to him I want to have at least a basic understanding of what I should be looking at. I have a radial arm saw but ripping 4x8 sheets on it is a pain, and my back won't allow me to handle 3/4 x 4 x 8 sheets anyhowAngry

Thanks,

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

  • Member since
    May 2010
  • From: SE. WI.
  • 8,253 posts
Posted by mbinsewi on Saturday, January 28, 2017 10:15 PM

3/4" plywood is usually 5 ply.  The different grades refer to what the finish is on the outside ply.  A/A, would be best, anything with B would be it has knots, but they have been filled, anything with C the knots show.  ( A/A, A/B, B/B, normally used for concrete forming), A/C, etc., and then you have CDX, which both sides are rough.

Maybe price out 1"x4" which is actually 3/4"x3 1/2" for your framing. This can be bought in different grades, which clear would be the best, with no knots, and grades that have knots, but are tight.  3/4 inch plywood can get pricey.  Treated 3/4" plywood is even more expensive.

Mike

EDIT:  Just seen you were in Canada, so I have no idea how grades are classified.

Good on both sides really has nothing to do with slivers, but what the actual finish of the top veneer is.

  • Member since
    July 2006
  • From: Bradford, Ontario
  • 15,797 posts
What type of plywood?
Posted by hon30critter on Saturday, January 28, 2017 9:59 PM

Hi gang:

I am considering using 3/4" plywood ripped into 4" strips to build my benchwork framing. I know I want G2S (Good 2 Sides) to minimize slivers etc., but I'm not overly familiar with plywood so I don't know how many plies I should be looking for. What do you suggest?

FYI, the layout will be in an insulated but unheated garage that is fairly well sealed. Cost, within reason, is not an issue. I figure I will need 6 - 4' x 8' sheets. I absolutely will not use OSB!

I spent some time searching Google and the forums but I couldn't find a clear answer as to what is available.

Thanks,

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!