''Can't see the Wood for the trees''

[lancelot]

HI folks,
now this is a very serious topic, so no laughter...
As some of you may know, I am in the process of building a ''Corliss'' engine...now this requires a foundation base of 32'' by
16'' by 86mm, suggested on the drawing as a ''laminated'' structure of different thicknesses of boards glued together to produce a flat non warpable surface...I went to my local joinery and asked them to produce this masterpiece, after much head scratching they decided on a four layer grooved edge jointed and glued laminate price to be agreed when time and costs worked out... a day or two later ... a phone call to confirm price of job...£100.00...GOODBYEEE...Next idea ...and this is where your Constructive ideas emerge...I decided to go for one very large piece of solid well Seasoned timber...namely a chunk of ELM 48'' by 24'' by4'' thick...this I will have machined and cut to the required size...now for the WOOD engineers amongst us... this piece of timber has about 10 years of seasoning ...should I treat the finished surface with a varnish or wax...as the engine is going to be bolted on to the wood should I use Stainless...AS I do not want the chance of the timber warping with a change in atsmophere conditions should it be supported in any way mechanically.
All ideas gratefully considered,
All the best for now,
John.

[paul]

This is probably a stoopid idea but what the hey.... why not use some more 'mature' er, 'timber' (layered as per the instructions if necessary) i.e. use some nice wood from old furniture? Old furniture with sound wood can be had for peanuts and has probably done all the warping it's going to do! 32x16x3.5 could be made from a nice oak, beech, walnut or whatever chest/wardrobe.

[dscott]

Now the great thing about timber is that we can predict which way it will warp by taking a look at the end. The way it is cut also helps or doesnot, and in hardwoods puts the price up
the closer to the centre of the tree. All outside bits tending to warp. Look allong a table and we see a happy bit of wood a sad bit a happy bit and a sad bit and so on, this balances out the warping. So lets veneer, this needs doing both sides otherwise we get a banana.
Now about Elm, we do get young trees growing but only up to a certain size then they die.
A piece the size you have must be at least 30 years old if it is from England. I can just about remember the Dutch Elm diesese striking in the early 70's.
I know in oak we use brass screws and you will often find in the packet of screws provided, a steel one to use as a pilot screw. Steel will rust like mad and stain.
Just a light waxing should do the trick for finishing.
David.
User of too much timber when hanging new doors all round the house, and all round mothers home as well, not to mention work. dont mention work, wood, metal, canvas, plastic, plaster clay, resin, rubber, concrete and cow poo.

[hat]

I can help with this one having a background in furniture making - well there is good and bad news.
Firstly lets get rid of the bad- elm is a very unstable timber compared with oak or mahogany - in the "good old days " its primary use was coffins because it took a good finish for the big day - but there wasn't much call for future maintenance.
However given it must be 20 years since it was felled providing it has not be exposed to sun rain and cold it should be fairly stable.
The finish is really up to you - but don't be tempted to finish one face only as this could create uneven possibilities for the moisture content to change and thereafter twist and warp the timber. I would suggest one coat or clear French polish all round - rubbed down with very fine wet and dry ( used dry) and then apply two coats of pure wax polish such as "Antiquwax" sold for furniture. Apply the wax with fine wire wool ( this might seem strange, but believe me!) then buff it between coats with a standard polishing cloth. Dont use any thing like Pledge because they contain silicones. The cross laminated idea seems crap to me - you might as well put it on a piece of plywood!

[GWRdriver]

John,
If I might describe an alternative . . . . this is a technique I've used in the past with some success and will use again, or some variation of it, for all future engines I build. Of course for the base size you need this could represent some expense, depending upon your local resources, but for smaller engine "footprints" I can usually beg cut-offs and scraps large enough to do the job.

The technique begins with the base box of your choice and the base in photograph is a simple box of mahagony plank. Set within this and blocked and glued in place is a sub-floor of good 3/4" plywood, the marine variety if I can find it, for stability and support. Again, suitable scraps can often be had at a local cabinetry shop.

Finally, let-in to the frame and laid in atop the sub-floor is a slab of cast polymer/acrylic solid-surface counter-top material, sold in the USA under various trade names such as "Corian." The most common thickness is 1/2", although 1/4" and 3/4" thicknesses are available and it's made in a many dozens of colors and textures. The color shown in the photo is a Corian eggshell white, the exact name of which I forget.

The "tiles", or rather the lines, in this example have been cut with a slitting saw, maybe .025" wide and no more than .040" deep, and then filled or "grouted" with a diluted and thinned paste of "Plastic Aluminum" thoroughly worked in. The only drawback of the material that I can find is that it's a rather brittle material and if not hollow ground and kept shallow the slitting saw can "pick" bits from the edges of the slits on the trailing edge of the cut. This will of course result in the grouted lines being ragged, but aside from the tendency to chip it machines (drills, mills, taps, etc.) very well.

The mfgs recommended method of finishing off machining marks in this material is to use a simple sanding block with 150gr or so paper and this will take off the excess grout also leaving a crisp tile line.

I drill, machine, or relieve the cast polymer sheet to make it the actual engine baseplate, just as I would if it was metal, and even the 1/4" material has proven to be very stable and will easily maintain engine alignment if supported on a good base and ply sub-floor.

I don't profess this to be cheaper across the board than what you've priced, but it certainly can be if soem of the components can be begged and scrounged. By the way, the engine in progress here is a pair of Stuart #10H's, altered and adapted to a twin configuration.

[Tel]

Just about exactly wot I was going to suggest Harry.

Or you could take the Jesse Livingston route (rocking valve engine) and cast a concrete base.

[spurley]

Hi John

You are getting some good advice here from the other forum members, may I suggest you contact John Mathews over here? He is an expert in timber, as you may know, and will doubtless be able to recommend what type of timber is best and wll probably have something in stock that you could negotiate a suitable price for.

I will help you get in touch with him if you wish?

Cheers

Brian

[lancelot]

Well folks, the ''die is cast'', I went and obtained a lump of Elm from our local Tree Surgeon at 48'' BY 24'' BY 4'' ,and when machined down to size looked great, total cost £50.00, not bad as far as timber prices and labour charges go .
The idea of laminating it myself from recycled timber is not feasible
as I do not have the skills, room, or machinery equiptment to do that nor to fabricate a base as G.W.R. suggested, TEL,s friend's idea of a Concrete base sounds good, at 32'' by 16'' by 3 1/2'', just a tad on the heavy side, there is going to be quite a lot of hole drilling and trench cutting in this block of wood, so I will wait until all this is finished before sealing the block with French polish and wax as Hat. suggested.
Let me thank you all for your suggestions and opinions,
All the best for now,
John.

[hat]

John , just a few final thoughts - perhaps you should give the block a coat of polish now to prevent the timber being marked with dirty hands etc - you can always get it off later with a cabinet scraper or a finely set plane. Second, beware of leaving it overnight face or bottom down on a concrete floor because despite its thickness it could warp or even split. It might be an idea to fix a couple of temporary battens across the underside ( across the grain) so that air can circulate under it until you are sure that is has stabilized. If you do fix them with screws drill tight screw holes at one end and slot the screw holes at the middle and other end to allow the block a small amount of movement - If you don't do this this it could create a bowing effect as the top side will unrestrained . With elm don't worry about using steel screws, its only materials with a high acid/tannin content that need brass. Such as Oak - If you decide to use brass screws drive home a steel screw first as Elm is tough and a high probability of shearing off brass screws exits. In any case the screw holes should be counter bored and lubricate the screws with a bit of soap ( when her indoors isn't looking)
Good luck!

[lancelot]

Thank you for the good advice,which I will certainly act upon.
One of the major reasons the Tree surgeon would not advise Oak was as you said, other timbers such as Beech or Sycamore were prone to splitting apparently, thus the reason I chose Elm.
All the best for now,
John.

[GWRdriver]

John,
I don't know about English oaks, but here in the southern US red oak is one of our most common hardwoods and it contains acids (tannic?) which when left in contact with bare ferrous metal will cause staining and discoloration, and eventually substantial rusting.

[houstonceng]

John

English oak isn't any different which is why one uses brass screws not steel - see previous mailings

Andy

[Noddy]

You've got your elm which is great. It's a beautiful looking timber.

Salvage timber seems to be in skips on almost every street. I was in Edinburgh the other week and a church was cutting up and skipping beech (now how the **** do you spell pews?). Unfortunately I didn't have the car and the management was furious at my skip diving in public...

For all beech is not pretty, I had an opinel penknife for 25 years that went everywhere with me (including having a cop try to arrest me for the "very serious criminal offence...a dangerous offensive weapon" (crap!)) and that beech handle never wore or split.
Keith