Sawn to PAR - how much to allow?

[MacGyver]

I am looking to buy some sawn sapele or red grandis for some window sashes. This will be my first big project and first time buying sawn.

I plan to buy 32 x 150mm sections, flatten one face and glue two lengths together to make larger, more stable sections. Once ripped and planed and thicknessed I hope to end up with two lengths of 44 x 58mm.

Does this sound reasonable? Would I be wasting too much wood? I had originally planned to buy 25mm thick but I asked the supplier and they said to expect to lose 6mm out of the 32mm which seems a lot to me.

Any advice much appreciated.

 

[Sideways]

A 6mm planing allowance doesn't sound bad to me. If the timber has much warp or bend over it's length it could easily be worse.

 

[niall Y]

I am looking to buy some sawn sapele or red grandis for some window sashes. This will be my first big project and first time buying sawn.

I plan to buy 32 x 150mm sections, flatten one face and glue two lengths together to make larger, more stable sections. Once ripped and planed and thicknessed I hope to end up with two lengths of 44 x 58mm.

Does this sound reasonable? Would I be wasting too much wood? I had originally planned to buy 25mm thick but I asked the supplier and they said to expect to lose 6mm out of the 32mm which seems a lot to me.

Any advice much appreciated.

50 X 50 PAR you can expect to finish 44 x 44. However, sash stiles in the past could be expected to finish closer to 1 7/8" x 1 7/8" - roughly 47 x 47

If you have control over the planing you can squeeze an extra few mm out of modern stock sizes. It is advisable cut your components roughly to length, then you won't be loosing too much off the thickness of your timber if you have to cope with bent stock
Some firms do offer to thickness sawn stock as " hit-and-miss", which would give you that bit extra to play with.

I'm not sure that, given the option of buying stock in the size you need, you should bother with sticking thinner pieces together, especially as it is being used for windows. I remember repairing windows for a customer on a fairly new house . The Western Red Cedar, timber had been glued together exactly as you have described and had separated out on the bottom rails. The maker had obviously tried to save money by using thinner stock. I think that one just has to reconcile oneself to the fact that the thicker the stock the more you will end up paying per cubic foot.

 

[Jacob]

Why the glue up? Extra work and you lose more timber planing 4 faces flat instead of 2. I used to buy a lot of 4x2" and 5x2" for sashes, aiming at finished sizes typically 44x44mm (stiles) and 69x44mm (bottom rails and everything else) i.e.you lose 6mm total for most planing from sawn to finish. Then various board sizes for the cases and 6x4" for the cills.
Always rip to sawn size and cut to length before planing.

 

[Daniel2]

Why the glue up? Extra work and you lose more timber planing 4 faces flat instead of 2. I used to buy a lot of 4x2" and 5x2" for sashes, aiming at finished sizes typically 44x44mm (stiles) and 69x44mm (bottom rails and everything else) i.e.you lose 6mm total for most planing from sawn to finish. Then various board sizes for the cases and 6x4" for the cills.
Always rip to sawn size and cut to length before planing.

I always cut a little oversize before planing. After planing, cut to exact dimension.

 

[Doug71]

Hardwood often comes in random widths, you might be able to get 150mm wide but I know if I ordered that from my supplier the minimum width piece might be 150mm but there would definitely be a few wider pieces among it and the off cuts often end up as waste.

I know the whole laminating thing is supposed to make it more stable but if you pick some nice straight grained pieces they shouldn't move much anyway.

It might be worth looking at Accoya, it's expensive but it does have a few benefits over Sapele. Accoya is very stable so you won't need to do the laminating thing, you can buy it in standard sizes so less waste and the dust from it isn't as offensive as dust from Sapele.

 

[Ollie78]

Is there a reason you don`t want to just get 50mm timber? 6mm is a fair estimate I buy sawn 50mm so its usually about 52mm really and I can normally get 44mm unless its super wonky.
Also look at Utile as well it is a bit less gnarly grained than sapele and what I use most of the time for sashes and front doors etc. very minimal waste and lovely to work with.
Accoya has been mad money for a while now, like black walnut money.

I have been using a bit of Abodo heat treated radiata pine for some things like box sash repairs and mouldings which is supposed to last well and is a third the price of Accoya but not been brave enough to make any sashes with it yet, it comes of the spindle crisp but is a little soft.

Ollie

 

[MacGyver]

Thanks for all the feedback. I went ahead and ordered the 32 x 150mm Red Grandis. I looked at the 50mm but it was twice the price, Accoya also far too expensive.

The glued joints from laminating two 32mm sections will be protected from the weather, one side in the DGU rebate and the other behind the stormproof seal.

The supplier phoned and confirmed half of the timber will likely be wider than 150mm but I am hoping to use the offcuts to make some of the muntins and bars.

Will update how I get on!

 

[HOJ]

Curious to know what your saving is by buying 2 pieces instead of one.

I do laminate sections, but to give me far bigger sections than the ones you a using:

 

[Diver Fred]

Not clear on what you mean by Sashes. Do you mean a complete 'Box Sash' including the fixed to the wall and the frames that slide up and down?
Or just the sliding part?
Or the sub frame that holds the glazing in a casement window? A.K.A Opening or Fixed LIGHT.

So if you are making the frames that hold the glazing, whether fixed, sliding or hinged I very much doubt that making such out of self-laminated (gluing lengths of timber together) will last for a number of years if exposed to the outside weather. Professionally laminated timber is glued together with different glues not available on the domestic market and pressed together at much higher pressures whilst drying/curing that you or I can achieve.

 

[Diver Fred]

Sizing - When I started helping my Dad (Time served Chippy) PAR would loose about 1/8-3/16 inch on the sawn sizing - equates to 1/16 to 3/32 per face. With metric sizing (and probably due to the quality of the timber) 3mm per face is or now seems to be normal.

Most timber I buy to make Lights out of finishes 44x44 or 47x44mm or for bottom rail 68x47 or 68x44. Have say the timber yard hates me turning up as I not only inspect for Shakes, Knots, twist and dead timber but get a ruler out to check the sizes.

 

[HOJ]

I do laminate sections, but to give me far bigger sections than the ones you a using:

Just to add some context to my post, this is the end result:

 

[johnnyb]

I wouldn't use glued sections if I could avoid it. In particular fully exposed things like gates.