Author Topic: Old School Sawmill Edger  (Read 9181 times)

Offline Brian Rupnow

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Old School Sawmill Edger
« on: October 16, 2019, 11:26:12 PM »
I'm all "engined out". I've been thinking about something to build and run with one of my engines. I already have a sawmill, a buzz saw, a steam donkey winch, a drag saw and a wood splitter. I have been thinking of an edger. Once a log has went thru the main-saw in a sawmill, the resulting boards have bark on the outer edges. This requires a second cut to be made to remove the strip on each side of the board which are known as "edgings". Old school edgers had two sawblades on a common shaft. One sawblade was "fixed" in position, while the other sawblade could be moved on the shaft to accommodate different board widths. They also had powered pressure rolls on the outfeed and infeed to draw the uncut board into the saws and to feed it out the other side when the cut was finished. A later development were "Bull-Edgers" which had multiple blades with spacers between them, so a wide board could be fed in and finish size narrower boards and two "edgings" would come out. The edgings on each side fell down onto a conveyor that took them to the chipper, while the boards passed on thru to the sorting shed to be sorted, graded, and stacked to dry. I think that one of the old style edgers might be fun to build. The blade on my buzz saw is about 3 3/8" diameter and I can cut "logs" of 1" diameter into stovewood lengths. (about 1 1/2" long). I want to do a bit of research and see if there are blades about 2" in diameter.--I could probably use slitting saws intended for metal work.
http://bbs.homeshopmachinist.net/thr...hlight=sawmill
http://bbs.homeshopmachinist.net/thr...hlight=sawmill
http://bbs.homeshopmachinist.net/thr...hlight=sawmill
http://bbs.homeshopmachinist.net/thr...ey+steam+winch
http://bbs.homeshopmachinist.net/thr...highlight=drag

Offline Brian Rupnow

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Re: Old School Sawmill Edger
« Reply #1 on: October 16, 2019, 11:26:49 PM »
Okay--Lets think about what I need. Engine with a governor--Yep, I have half a dozen of those. 2" diameter sawblades--Yep, I can order them from Proxon or Harbor Freight. Shafting will be cold rolled steel in "stock" sizes . One sawblade is fixed--no problem. One sawblade has to be able to slide along the shaft but still be powered by the shaft, to adjust for different board widths. Maybe a double keyway, one on both sides of the shaft and long keys, with two keyways in the moveable sawblade hub.Two powered rolls, and two pressure rolls for infeed and outfeed. Not sure at the moment, but maybe diamond knurl 4 pieces of cold rolled steel to act as textured finish on rolls. Some profiled pieces of flatbar to act as anti-kickbacks on the infeed side of the edger. A frame to hold all the bearings and shafts, etc, in place. An infeed and an outfeed table---This is where I broke one of my own rules---NEVER THROW ANYTHING AWAY!!! When I was building my sawmill, some kind fellow in USA sent me a whole bag of 3/4" square oak. I used it to build my sawmill carriage, and hung the bag with the rest of the oak on a nail in my storage closet. Couple of years ago in a cleaning frenzy, I thought, "Aw heck, I'm never going to use that stuff", so I pitched it out. Dumb Bastard!!! The sawblades are going to have to run at engine speed 1200 rpm or a bit faster. The infeed and outfeed rollers are going to have to run at considerably lower speeds, so some gearing is going to be called for. What have I missed?---Brian

Offline Brian Rupnow

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Re: Old School Sawmill Edger
« Reply #2 on: October 16, 2019, 11:27:47 PM »
A bit of preliminary layout work shows the two 2" diameter Proxxon blades. Since the center hole on these blades comes in at 13/32" diameter, that pretty well dictates the size of hub I can have. And of course, the hub outer diameter  pretty much dictates what the hub inner diameter can be. This in turn, dictates the size the shaft will be. Turns out I can use a 1/4" diameter shaft, which should work fine. The fixed blade is going to be locked in one position on the shaft. The moveable blade (which is moved to accommodate different board widths) must be driven in sync with the fixed blade, so to do that we have a couple of long keyways in the shaft, and a couple of keyways in the hub of the moveable blade assembly. As in all designs, the project must start with the items which are purchased and then the size of everything around the purchased components is "custom sized" to accommodate the purchased part, which in this case is the sawblades.

Offline Brian Rupnow

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Re: Old School Sawmill Edger
« Reply #3 on: October 16, 2019, 11:28:25 PM »
The edger has two driven rollers as shown, along with two pressure rollers from the top (not shown). The position of the top side of these driven rollers is determined by the fact that the underside of the board passing thru the edger does not interfere with the hubs on the saw blades. Positioning in the other plane is established by the fact that you don't want them so close to the sawblade that they touch it, and you don't want them so far away from the blade that the board will "bend" when it encounters the blade.

Offline Brian Rupnow

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Re: Old School Sawmill Edger
« Reply #4 on: October 16, 2019, 11:29:02 PM »
Locating all of the rollers and bearings lets me then design a frame to support everything. Still have to design infeed and outfeed tables and a "fence" to guide the board straight into the rollers. This all goes very rapidly, but will slow down a bit when I start adding the belts and sprockets which power the saw and the bottom rollers.

Offline Brian Rupnow

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Re: Old School Sawmill Edger
« Reply #5 on: October 16, 2019, 11:29:29 PM »
Add in an infeed table and an outfeed table, along with a material guide/fence, and that's almost got it. Only things missing are the anti-kickback fingers on the infeed side and the drives.

Offline Brian Rupnow

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Re: Old School Sawmill Edger
« Reply #6 on: October 16, 2019, 11:30:00 PM »
Looking up from underneath you can see the long handle sticking out at the infeed end. This handle position is adjusted by the "edger man" to change the distance between the saw blades to cut different widths of board.

Offline Brian Rupnow

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Re: Old School Sawmill Edger
« Reply #7 on: October 16, 2019, 11:30:34 PM »
Today I am working on the drive for the saw blades and for the infeed and outfeed rollers. The rollers will operate at a much lower speed than the sawblade. This calls for a bit of trickery. In this picture you see a gear reducer I built about 10 years ago, with a sprocket on the output shaft. As positioned it would provide a great drive for the rollers, but any drive to the sawblades is totally blocked. I've had that small 8:1 gearbox setting around here for ten years, but today is the first time that I've actually went ahead and modelled it.

Offline Brian Rupnow

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Re: Old School Sawmill Edger
« Reply #8 on: October 16, 2019, 11:33:34 PM »
 The rollers under the board and the sawblades have to rotate different directions. Best way to address that is with a bit of overhead lineshaft. The engine, clutch, and gear reducer all parts that I currently have setting in my office.
« Last Edit: November 03, 2019, 04:35:56 PM by Brian Rupnow »

Offline crueby

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Re: Old School Sawmill Edger
« Reply #9 on: October 17, 2019, 12:34:32 AM »
I love your design process, working out a seemingly simple machine with lots of little complexity. Will be following along...


 :popcorn:

Offline Brian Rupnow

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Re: Old School Sawmill Edger
« Reply #10 on: October 17, 2019, 02:59:39 PM »
I had to do some calling around to my old sawmill contacts, but I finally come up with a good edger man.
« Last Edit: November 16, 2019, 04:12:09 PM by Brian Rupnow »

Offline crueby

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Re: Old School Sawmill Edger
« Reply #11 on: October 17, 2019, 03:11:23 PM »
He needed proper safety gear - ear muffs and glasses!


Offline Jasonb

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Re: Old School Sawmill Edger
« Reply #12 on: October 17, 2019, 05:21:20 PM »
What is the point of the two high up gears? at 1:1 they don't look to do anything so you could just as well run the output pulley on the same shaft as the input.

Could also save a lot of drag by just taking the drive into the blade and gearing down on the same side to drive the rollers, changing direction with the gears if needed.

Offline crueby

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Re: Old School Sawmill Edger
« Reply #13 on: October 17, 2019, 05:32:25 PM »
What is the point of the two high up gears? at 1:1 they don't look to do anything so you could just as well run the output pulley on the same shaft as the input.

Could also save a lot of drag by just taking the drive into the blade and gearing down on the same side to drive the rollers, changing direction with the gears if needed.
I think they are there to change directions, the belt coming down on the far side goes the opposite direction as the belt on the near side, one to run blade and one to run feed rollers.

Offline Jasonb

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Re: Old School Sawmill Edger
« Reply #14 on: October 17, 2019, 06:48:15 PM »
That's why I said the gearbox could also change direction.

But there does seem to be a lot of shafts and pullies that are not needed, just needs a simple up and under belt to drive the two rollers off the blade shaft, small drive and large feed roller pulleys makes sure the blade spins up and the wood feeds through slowly.

Infeed and outfeed fences should also be offset and the "L" shaped outfeed fence won't work
« Last Edit: October 17, 2019, 06:54:01 PM by Jasonb »