Finger jointing waste

[Dominique Meuris]

At this moment I have around 25m3 of oak remains that are to good to throw in the heating but to short to use in our products.

Recently I have found a new customer who doesn't mind having some parts with fingerjointed pieces. That's what made me think to start doing this.
I just have a few questions about it.

What is the most efficient way of making them?
I was thinking of using a head like these on a spindle moulder with a sliding table.
http://www.bovenfrezenshop.nl/p/15741/verlijmfrees-d105-x-496-x-30/

But how do I glue these together the most efficiently?
Applying glue piece by piece is taking a long time, but this is something i can live with.
But for pressing them?
I can put them on a horizontal pneumatic glue press. and then glue piece by piece. or a certain length piece by piece.
or what do you suggest?

[scott vroom]

Oak is inexpensive....I can't imagine a scenario where it would be cost effective to finger joint scrap into usable length boards (assuming your time has some value). Perhaps I'm not understanding your objective?

[Keith Hankins]

I'd agree unless your time is worthless :). Now if the scrap is 8/4" or better thats a diff story. Table/bench tops come to mind and they would be worth it IMO, but that and a buck fifty will get you a cup of coffee. Cheers!

[Dominique Meuris]

I'd agree unless your time is worthless :). Now if the scrap is 8/4" or better thats a diff story. Table/bench tops come to mind and they would be worth it IMO, but that and a buck fifty will get you a cup of coffee. Cheers!

All the parts i'm talking about are atleast 15cm long, all the rest is firewood and not considered as remains.
And the finger jointed parts will be used for hidden vertical wall's, shelves, ...

and well if oak is worthless, 25m3 * 750 € = 18750€
my workers aren't costing me to much houre considering, but ofcourse it still needs to be as time effective as possible.

[scott vroom]

First off, your scrap wood cannot be valued at retail. As a matter of fact, the value of the scrap wood is irrelevant to your analysis. The only meaningful calculation in this situation is the total cost to rework the scrap vs the expected revenue the finger jointed boards will generate. If you believe you can generate an acceptable return on capital and labor by doing the rework then you must next consider the opportunity cost of tying up your labor and equipment to gerate marginal revenue from reworking the scrap. Could your labor and equipment be used in other ways that would provide a greater return to the business?

[Andrew Pitonyak]

First off, your scrap wood cannot be valued at retail.

Although you are correct, the way I would value it would be to say "hey, I can avoid purchasing this much wood if I do this", so, it is not a question of what the scraps are literally worth, but rather, how much he does not need to spend purchasing and preparing new wood compared to what he spends processing the small scraps.

I have seen that type of joint often in long moldings; for example, in the moldings around the garage car doors in my area.

[Peter Quinn]

Are you butting shorts or edge gluing or both? They are calling that cutter you referenced a finger joint cutter in English, bad translation, it's not meant for but joints on length, it's to aid in gluing edge to edge. Butting ends requires a wedge type finger jointer with longer fingers. I've done it on a sliding shaper and clamped with a simple plywood jig, very slow but effective. Can't imagine make a lot of it without specialized equipment. Rf glue dryer would help, pneumatic finger joint glue injector like a prazi would speed it up, a pneumatic press would help too. I used pipe clamps. Cost it out carefully, the best use of your time and wood might be to make kindling!

[scott vroom]

Although you are correct, the way I would value it would be to say "hey, I can avoid purchasing this much wood if I do this", so, it is not a question of what the scraps are literally worth, but rather, how much he does not need to spend purchasing and preparing new wood compared to what he spends processing the small scraps.



You're partly correct. The $ amount of wood you could avoid purchasing by reworking scrap would be equal to the gross margin from the sale of the rework, which is essentially what I stated. What you're missing is the analysis of whether he could produce more profit reworking and selling scrap Vs. producing the primary business product. In that regard, the original bd foot cost from which the scrap was generated is completely irrelevant. For example, if the OP was able to generate $5,000 profit from 2 full weeks of scrap rework but doing so caused him to pass on the opportunity to build new cabinets that would have generated $8,000 profit during that same period then the rework was likely a bad business decision. I'm assuming the OP is a businessman and not a hobby woodworker. His time and his labor/equipment do have value.

[Larry Fox]

Very much in Scott's camp on this one. At least around here, I don't think it is possible to produce usable length components in the manner you describe which is in any way close to being as cheap as buying oak lumber - not even close. Discounting tooling, materials (glue, equipment maintenance, etc), opportunity cost, labor cost - think about what you are doing (or asking someone else to do). You are essentially taking scraps that come from larger projects and which are a coin flip as to whether or not you thrown them into the fireplace - milling them, gluing them together, re-milling them into components that are going to be parts to a larger project. Sounds terribly tedious to me and if I were asked to do this by my employer I would do it for exactly as long as it took me to find a new gig.

Also, you mention that all the scrap pieces are t least 15cm in length. Google tells me that this is 5.9 inches. A shorts pile is one thing but, in any of the common species, anything less than about 20" (~50cm) is firewood. To finger joint it you need to figure out a way to get something <6" through a spinning shaper head safely - twice.

For my $, €, gbp, whatever I am tossing them into the fireplace or donating them to someone who can use them and going to the lumber yard for some boards.

[J.R. Rutter]

Automated finger jointing lines can churn out a couple of lineal m/min of finished boards, but of course the initial cost is high. See GRECON/Weinig for example. That is the level of equipment that makes finger jointed poplar cost effective here in the US. Talk about cheap wood! Without the high volume, I agree that it is difficult to make manual methods pencil out. If anyone has it figured out, it is probably the Chinese. So maybe you could find some Asian manufacturer with a modular system that requires unskilled labor to operate.

[Dave Cullen]

I have seen large dowels, used for closet poles, made with finger jointed pine. If some manufacturer decided that this was cost effective, I could imagine that gluing up oak scraps might also be. I also imagine that they have a machine that does this in a few seconds. This seems to me to be the crux of the matter - can it be done quickly and painlessly such that it's worth doing.

[Keith Hankins]

All the parts i'm talking about are atleast 15cm long, all the rest is firewood and not considered as remains.
And the finger jointed parts will be used for hidden vertical wall's, shelves, ...

and well if oak is worthless, 25m3 * 750 € = 18750€
my workers aren't costing me to much houre considering, but ofcourse it still needs to be as time effective as possible.

Google time value of money. Take into account opportunity cost, materials etc. In the end if you don't count your time (i use to but don't anymore) and ignore material costs i.e glue electricity, etc it could be worth it, but I seriously doubt it unless you have an extreme large quantity or can automate the process (which would require investment).

[Dominique Meuris]

Google time value of money. Take into account opportunity cost, materials etc. In the end if you don't count your time (i use to but don't anymore) and ignore material costs i.e glue electricity, etc it could be worth it, but I seriously doubt it unless you have an extreme large quantity or can automate the process (which would require investment).

Well I must say that I aggree with what everyone is saying here.
ofcourse there's a huge amount of costs in labour, glue, knife sharpening, electricity, ...
But at this moment since we are in a country with low salary costs I think it would be usefull to produce these pieces. or atleast give it a try.
All of these pieces are 20mm thickness or 30mm thickness. and complete defect free, no cracks, no knuts, not anything, ...
because we select our timber very carefully.
starting from fresh timber we use only 25% in a finished product. 10% is sold as B-quality timber. 55% is sawdust + waste "C-quality is waste aswell", 10% are the remains i'm talking about now. on average they are between 15-45cm long.

I'm going to try to make them on a spindle shaper? the only thing I would need suggestions for is the clamping.
Mostly I will need the pieces to be glued to boards of 120cm length.

any suggestions for the clamping?

[Peter Quinn]

It strikes me as odd that a piece of lumber that is glued up from shorts into a board should be thought of as free of defects while a board with a knot would be considered in some way inferior? I trust wood much more than glue. To me the onslaught of finger joint mostly Chinese junk on the market is the lowest level of production. Take it a few steps further and turn it into a veneered product with solid core and it takes on a whole new meaning, such as in door cores or solid core sheet goods.

As far as clamping my experience was you need to control all three planes simultaneously, and glue up in stages. I could easily glue 220cm length, the other dimensions were 19mmX50mm, each piece was about 50cm length. I made staves, then flipped every other stave 180 degrees to stagger the finger joints for the edge jointing procedure. My species was mahogany, the product was a door core to be veneered with quarter sawn oak. I made a jig (several actually) with two long maple boards set 19mm apart,screwed to a piece of VC plywood, the maple was 50mmX50mm just a bit shorter than the total glue up length. Pipe clamp provided the pressure, suppose I could have used a jack screw on one end and pushed against a stop? I had a few toggle clamps in the middle to keep the glue up form bowing off the jig. I left the pieces in clamps about 45 minutes, plenty of glue so they weren't starved.

To mill the finger joints I used a sliding spindle molder with an eccentric clamp that is built in to it, could easily have made a plywood sled with a few toggle clamps as the parts were not long. one end face up, spin, the other end face down. Setting up a finger joint for perfect alignment is not a joy, but once set its pretty easy to use. I'm sure there is a trick to quick set up, I just don't know what it is.

[Kent A Bathurst]

I was thinking of using a head like these on a spindle moulder with a sliding table.
http://www.bovenfrezenshop.nl/p/15741/verlijmfrees-d105-x-496-x-30/

That is the general idea. That profile is for edges. For end-to end, you need much deeper cuts. Two very different examples are:

http://www.toolstoday.com/p-5480-insert-finger-joint-cutter.aspx

http://www.rockler.com/finger-joint-router-bit?utm_source=google&utm_medium=cpc&utm_term=&utm_content=pla&utm_campaign=PL&sid=V9146&gclid=CNDKydiYp8ACFVQV7Aodmw0A_A

There is automated industrial equipment for fingerjoints, but these are very expensive, and very complicated,


But how do I glue these together the most efficiently?
Applying glue piece by piece is taking a long time, but this is something i can live with.
But for pressing them?

You can see in the links that the depth of the cut is perhaps 1". So - the effective length of each piece is shortened by 2" or 5cm. Plus - you have to be able to press the joints together.

The standard method for doing this is accumulating pieces, in a track or tray that holds the sides straight, and holds the pieces down. Then a hydraulic press that squeezes them all together. They don't have to be held till cure - the friction fit of the joints does that.

YOu have to experiment, but the number of pieces that are accumulated is whatever is required to get to a standard finished length.

For example, if the pieces averaged 10"/25 cm, the effective length is 8"/20cm. If you want to produce a standard size of 6 ft/200cm, you would have an average of 9 pieces. Squeeze them together. after they cure, trim the ends ack to a consistent 200cm.

At this moment I have around 25m3 of oak remains...........





25m3 is quite a bit of wood. If all the pieces are 25cm long x 10cm wide x 2.5 cm thick, then one cubic meter has about 1,600 pieces. 25m3 is 40,000 pieces.

The real question is this: How long does it take you to accumulate 1m3??

[Jack Vines]

The local production cabinet house here, Huntwood, turns out miles of end-then-edge-glue-jointed oak, cherry, walnut, birch, maple and other hardwood cutting boards and countertops. They don't throw away anything but sawdust. No idea as to the capital investment involved, but making large boards out of many smaller ones is obviously cost-effective if done on a large enough scale.

Another FWIW, consider true butcher-block (end-grain-up) cutting boards and kitchen islands. They sell well and a great way to use up short lengths.

jack vines

[Chris Padilla]

I think Jack is onto something here: making something WITH the shorts is better than trying to make longer boards out of them.

https://www.youtube.com/watch?v=gliOZyHkdps Here is a pretty sweet cutting board.