Author Topic: Model Woodsplitter  (Read 19983 times)

Online Brian Rupnow

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Re: Model Woodsplitter
« Reply #15 on: January 30, 2015, 05:21:11 PM »
These will make perfect "hold down" bearings to ride against the back of the rack to keep it engaged with the pinion. They are router follower bearings. These are what I use for cam followers on some engines I build.

Offline mklotz

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Re: Model Woodsplitter
« Reply #16 on: January 30, 2015, 05:26:18 PM »
I've never used a powered wood splitter but I would think that too thin an angle on the wedge would run the risk of it "sticking" in the wood.  A larger angle would force the wood apart more and it's that action that forces the split to propagate along the log.  If you split a piece of wood with a wedge you'll see that the separation of the two pieces is happening well ahead of the point of the wedge.

It's likely a problem the solution of which depends on the splitter kinematics and the wood type and condition.  An experimental approach is definitely indicated.

Is the edge of the wedge going to lean out at the top to force the log to stay on the splitter as well as making the entry of the edge into the log progressive to reduce the force needed?

Do they sell balsa dowels?
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Regards, Marv


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Offline Tennessee Whiskey

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Re: Model Woodsplitter
« Reply #17 on: January 30, 2015, 07:42:32 PM »
Brian,  I know you are going to think I'm full of crap ( think, you already know :D), but, I was thinking about your sawmill just the other day and thought wonder if he has thought about a splitter.  I like the route you are looking at now. I agree with Marv, after using one a good bit, I notice the least bit of an unsquare cut on the log and it wants to rise. A wedge with some rake on it may just solve this and I'm probably going to try it in full scale.  Thanks for the DR video also.  To me it seems they have built a machine using very old technology with modern power.  It seemed strange to see two big spinning flywheels on a modern piece.  Replace that engine with a stationary ( with fly ball govenor ) and flat belt  and let it bark.  :thinking:

Eric

Online Brian Rupnow

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Re: Model Woodsplitter
« Reply #18 on: January 30, 2015, 08:28:05 PM »
The links and activation arm are all sussed out. The yellow bearing support plate and flywheel that fit on the near side are hidden so you can see the linkage. About all that is left to do is model in the return springs for the ram.

Offline Tennessee Whiskey

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Re: Model Woodsplitter
« Reply #19 on: January 30, 2015, 08:46:31 PM »
Brian, other than just adding another movement, I think it would work with the roller just placed into the " activation arm". The operator is going to have to hold pressure either way. 

Eric

Online Brian Rupnow

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Re: Model Woodsplitter
« Reply #20 on: January 30, 2015, 08:57:02 PM »
Not so, Eric--It is a "cam over" arrangement, and locks in the forward position when activated until the end of stroke is reached. Well---maybe not. I just watched the video again and he does have to hold the handle. Perhaps it's just set up this way so that he doesn't have to hold a lot of pressure on the handle.--I see that there is an adjustment bolt, so it probably could be adjusted to be a cam over style, but that would contravene a whole ton of safety and liability laws.
« Last Edit: January 30, 2015, 09:05:30 PM by Brian Rupnow »

Offline Tennessee Whiskey

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Re: Model Woodsplitter
« Reply #21 on: January 30, 2015, 09:13:11 PM »
Will there be a type of trip to unlock the rollover on the cam at the end of the stroke or will the operator do it?

Eric

Offline Tennessee Whiskey

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Re: Model Woodsplitter
« Reply #22 on: January 30, 2015, 09:15:13 PM »
Must have crossed our post. I'm watching

Eric

Online Brian Rupnow

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Re: Model Woodsplitter
« Reply #23 on: January 30, 2015, 09:57:09 PM »
So there we have it, return springs and all. My software counts a total of 21 parts. 2 of those parts are the return springs, and two are the flywheels which I already have, one is the rack which I already have, and two are the router bearings . That leaves 14 parts to be fabricated.
The flywheels aren't really wide enough for a belt drive at only 1/2" wide, so I might have to think about a pulley. I would like to have my flywheels turning at 300 rpm, and the powerband of my engine is at about 1200 rpm, so  if I could drive it to one of the flywheels with an o-ring drive with the 1" diameter pulley already on the Webster, that   would work out perfect.

Online Brian Rupnow

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Re: Model Woodsplitter
« Reply #24 on: January 30, 2015, 09:58:23 PM »
Yes, there will be a trip to disengage the rack from the pinion at the end of the stroke. The springs will pull the ram back into the home position. Eric--Go back to post #9 and watch the video--all of the action is very visible.
« Last Edit: January 30, 2015, 10:06:43 PM by Brian Rupnow »

Offline Tennessee Whiskey

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Re: Model Woodsplitter
« Reply #25 on: January 31, 2015, 12:24:13 AM »
Brian, I saw how they did it, but, I am waiting for the "Rupnowism " version  now  8)

Eric

Online Brian Rupnow

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Re: Model Woodsplitter
« Reply #26 on: January 31, 2015, 01:24:13 AM »
Eric--I spent an hour today laying out the linkages, and figuring how the release mechanism worked in the video. If I can, I am going to exactly replicate the action in the video. One of the nice things about having a 3D software package that lets me make kinetic models. Of course, working from ratios and relationships viewed on a video does involve an element of guess-work.----brian

Online Brian Rupnow

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Re: Model Woodsplitter
« Reply #27 on: January 31, 2015, 03:28:26 PM »
All of the modelling is completed. Bushings have been added to the bearing plates, keyways to the pinion shaft and flywheels, and a stop bolt assembly to adjust the swing of the engagement linkage. Also, a cross dowel has been fitted through the main support body to limit the back travel of the rack and pusher assembly. In the current view, the handle is in the engaged position and the router bearings are pressing on the flat back side of the rack, forcing it down into engagement with the pinion gear.

Online Brian Rupnow

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Re: Model Woodsplitter
« Reply #28 on: January 31, 2015, 05:57:23 PM »
I think perhaps the most interesting part of this build, for me, will be the linkages. Most of the plates, etcetera are just basic shapes with clearance or tapped holes in them. The gear is complex enough if you haven't made two dozen gears already on other projects. The links are in a way, new ground for me to cover. This particular link will be made of steel. The only trick part may be turning the bosses. Again, the standard warning applies about these drawings--Do Not Copy them!!! There may be errors that I won't discover until later in the build. All drawings will be updated, and a download link provided at the end of the job.

Offline Roger B

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Re: Model Woodsplitter
« Reply #29 on: January 31, 2015, 06:07:24 PM »
A very interesting concept  :ThumbsUp:  :ThumbsUp: I will be following along and waiting for you to split the first firewood for Crueby's Shay  ;)
Best regards

Roger