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Sawmill Build - Planning Stages

Started by sdboers, November 01, 2018, 01:21:38 PM

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sdboers

Hey Folks,
  There is a wealth of knowledge on this forum and I would like your assistance.  I welcome your advice and criticisms.
 
  It's looking like I'm going to embark on a sawmill build in the spring.  I started down this path a couple years ago by contracting someone to build the head, and I would take care of building the log bed.  Long story short - I'm not satisfied with the head that was delivered and have only sliced one log with it.  I'd rather not put more money into it - I think simply starting again myself is a better idea - salvaging the parts I want to keep.  I don't consider it a failed venture at all...  I got way more value in parts than the build actually cost - so I still came out ahead.  Also gave me a better chance to understand what I liked and didn't like about the build that was delivered.
 
I've done a ton of reading and researching in the meantime and have learned a lot - but there is still a lot left to learn.  That's where you come in!!  :)  I'd like to spend the winter collecting the parts I need and finalizing the design.  I've already sketched out the whole thing - but I'm certain there are things I haven't thought of - and things that could probably be done in a better way.
 
Given the parts I'll be able to strip from the existing head - I estimate it will cost me about $2500 CAD to fully complete the build.
 
The basic specs of what I'm trying to build are as follows:
• Engine: 21hp Honda GX-630
• Max cut width: 34"
• Max cut depth: 12"
• Max cut length: 16'

Parts I already have:
• Engine
• V-groove wheels
• 4" centrifugal clutch
• A bunch of metal to re-use
• 2000lb winch
• 3500lb winch
• Manual brake winch
• 90% of a functional log bed
• And probably a few things I forgot
 

To me - the biggest failings on the current head are:
  • Hate the band wheels - they are pressed steel and don't feel strong and safe to me
• Blade guides - only adjust left and right - no other adjustments
• Can't operate the hand winch, throttle or lube from the ground
• Cable lift binds on itself slightly (cable crosses over itself) causing the head to lurch a bit when raising and lowering (hard to be precise)


Here is the design I have come up with so far - but I really can't take credit for all of it.  I have purchased 2 different sets of plans I have gleaned information from.  I have watch 2.7 million how-to videos (ok - I exaggerate).  I have looked at all kinds of commercial saws.



 

 

 

Happy to go into any of the details - a few items:

  • Head lift is chain \ electric winch.  I figured I would chain lift from all 4 corners via sprockets and drives at the top
  • Blade tension is by a hydraulic hand pump \ porta-ram with gauge.  Overkill, but measurable and precise
  • Blade tracking is via a hinged plate on the idle wheel
  • Blade guides - I'd probably source these from Cook Saw - they are quite nice...
  • Would go with 19" cast iron pulleys from Surplus Center for the band wheels
  • Log stops go up and down individually via a crank handle on the operator side

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

Crusarius

cable lifting all 4 corners is unnecessary and will prove a royal pain to get to lift without binding. 2 corners should work fine. It looks like you will be much better balanced than my build with the location of the saw compared to the rest. 

 Hopefully the brake on the winch will be sufficient to hold the weight of the head where you stop it. Be a shame to have it wander during a cut.

Two axles is unnecessary. Woodmizers LT40 is a heavy beast and still only uses 1 axle.

I am looking forward to this build. I like what you have going so far. One other suggestion I would make is removable tongue on the trailer. It is so much nicer to walk to the other side of the mill without having to walk around it. Especially since I have the operator side opposite the crank to raise and lower the backstops.

sdboers

Hey Crusarius,
  Thanks for the reply.  I have some responses below...

I was going to go with chain lifts over the cable lifts to solve the binding problem.  Chains of equal length, and pinned with an adjustable eye bolt at the end.  Should make the lifting a lot more precise and easier to adjust than with a cable.  That being said - you might be right.  Lifting all four corners may be over kill.  I could easily start with two and see how that worked out - add the other two if its not very well balanced.  If the brake on the winch won't hold it - I figure I'll add a cam lock \ or toggle clamp to the head.

The trailer already has two axles, so I figured I would simply leave them there.  They aren't in the best shape, so I wouldn't want to take them on the highway.  If I decide to replace them, maybe I'll downgrade to a single better axle.

I do like your suggestion on the removable tongue.  The current trailer ends at the pointed part with a pin mount.  I was going to extend it to a trailer coupler for easier towing - I'll make that part removable as suggested.

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

mike_belben

I agree the 4 telescoping posts will be sticky..2 telescopes and maybe 2 with roller guides would work if you really need all 4 posts.  

 A sprocket can be its own brake.  Slide a pin into a hole behind the sprocket the hold the shaft in place.  The chain will be over the top but the bottom teeth are exposed.  Drill a hole behind that and poke in a screwdriver that binds it.
Praise The Lord

Crusarius

Just remove 2 tires from the axle. that way you have a full axle worth of spare parts :)

Crusarius

Look at hud-son sawmills. They have 4 posts but really only use 2. the other 2 are just to support the mast. They are super lightweight and still surprisingly rigid.

sdboers

Ok - I'm going to re-think the 4 telescoping posts a bit.  I like the 4 post design - but I hear whats being said about binding.  I'll look for some good pictures \ videos of the hudson mill to take a good look.

At the moment it sounds like either telescope on 2 posts only - or alter the second 2 to use rollers to avoid binding.

2 strands of #50 chain is more than strong enough to lift the whole head - perhaps it is just a matter of finding the balance point once assembled and lifting from there.

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

sdboers

Incidentally - material wise - I was going to use 2x2 x 3/16 wall for the uprights and cross members.  The overlay sliding portion was going to be 2 1/2 x 2 1/2 with 0.215 walls.  That would leave a 0.035" gap all the way around.

Too loose to be precise?  Too tight to cause binding?

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

Joe Hillmann

Quote from: sdboers on November 01, 2018, 04:21:02 PM
Ok - I'm going to re-think the 4 telescoping posts a bit.  I like the 4 post design - but I hear whats being said about binding.  I'll look for some good pictures \ videos of the hudson mill to take a good look.

At the moment it sounds like either telescope on 2 posts only - or alter the second 2 to use rollers to avoid binding.

2 strands of #50 chain is more than strong enough to lift the whole head - perhaps it is just a matter of finding the balance point once assembled and lifting from there.

Sean.
I originally built my mill with two posts that the head went up and down on.  I don't remember now why but for some reason I ended adding two more posts, the head doesn't slide on the back two but for some reason I decided I needed them.  I think the reason may be because I couldn't run a bar directly across the top of the two main beams because the engine would hit it when raised so instead I made a C shaped beam between the two posts and added two more smaller posts behind them to stiffen it up.  I also intended to add a bunch of 45 degree bracing on the two smaller posts and the C shape bar on top but never did.

sdboers

Maybe I should just be a rebel and try the four sliding posts...   8)  I gotta be me!! lol...  I could report back with the results - ready to cut them out when you guys will have the opportunity to say -"yep - told ya so..."

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

sdboers

Interesting...  Some of the Hudson mills are actually 6 posts.  A 4 post cage - and then 2 posts in between that the head rides up and down on.  So - as was mentioned - they still only telescope on 2 posts.  Things that make you go hmmm....

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

mike_belben

Its the issue of welding them and having them pull out of square during the process. 2 guide posts is half the trouble of 4 to keep in square with each other and sufficent for the job.   Additional uprights to mount components is fine but theres no real need for 4 telescope points in small mills and it increases the odds one will go out of square with the others in some plane unless you have a jig table or platten.  Most guys dont. 
Praise The Lord

FloridaMike

I like most of your design! 

I do wonder if your idle band wheel will be crowding your log opening, due to being mounted near the saw head upright?  Could make clearance tight for mounting the roller guide on that side.

I think two posts with 2.5" slides over 2" and two 2" posts with rollers would work great.

I'm having a mental image block, seeing where the slack side of the chain goes as the head goes up?    
Mike

sdboers

Quote from: mike_belben on November 01, 2018, 07:47:56 PM
Its the issue of welding them and having them pull out of square during the process. 2 guide posts is half the trouble of 4 to keep in square with each other and sufficent for the job.   Additional uprights to mount components is fine but theres no real need for 4 telescope points in small mills and it increases the odds one will go out of square with the others in some plane unless you have a jig table or platten.  Most guys dont.
Mike - that makes perfect sense.  I better understand the reservation about four slides now.  Appreciate the explanation.

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

mike_belben

If you wanna do 4, make it a bolt together affair.  That way you can shim or slot holes to get back in plumb/sq etc. 
Praise The Lord

sdboers

Also a good idea.  Not sure how I'll proceed yet - but I like the ideas that are coming out.  Rollers, bolted, stick with 2 posts.  All very good suggestions.

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

JRWoodchuck

I started out with four sliders. Im not a machinist turns out I quickly cut the back two off. The longer your sleeved pieces are the less chance it will bind and have less play forward and back. Seems like mine are 12ish inches. If I rea did it I would make them longer. 
Home built bandsaw mill still trying find the owners manual!

charles mann

I too am building a mill. Mine will be a 4 post as well, only bc of cut size and power plant. I will be using 2 2 1/2" 4140 rods with 2 12" 4"x4"x3/16" sq tubing with 2 pcs of UHMW per tubing, with a hole bored in it to slide up/down the rods. 
I will also have clearance issues bc of my pwr plant, so im going to incorporate a lil of the TK 2500 and the WM LX 450 carriage design. 

Being nearly 11' wide for the saw beam and 9' tall for the carriage, i know i will initailly have warping issues during the welding process. So im going to tack an extra 3"x3"x1/4" sq tubing on 2 sides of the posts, letting the 1 post cool down completely before grinding the extra stiffener posts off and tacking them on the opposing post catty corner to to the previously welded post. If warpping still happens, ill run a few beads down the warpped post to draw the metal back the other direction. 
Temple, Tx
Fire Fighting and Heavy Lift Helicopter Mech
Helicopter and Fixed Wing Pilot

sdboers

11 feet wide??  That sounds massive!

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

sdboers

Ok - so there seemed to be a pretty good consensus that I'd have binding problems with 4 telescoping tubes.  The advice was to look at some type of roller guide for the back posts.  Below is what I've come up with using linear guide rails commonly used in the CNC routing and machining area.

If you're not familiar with what they look like - here's a picture:


 

And here is a picture of them incorporated into my 4 post design.  The front two posts will remain telescoping tube, the back two will be changed over to the linear guide rails.  I suppose I could switch all 4 and make the whole head lift on bearing slides.



 

What do folks think of this change?  Think it avoids the binding issues?

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

Crusarius

I see money. Lots of money. and you will definitely need a set of wipers on top and bottom side of the linear bearings. My only real concern is how well the linear bearing will hold up to the weather. Some sawdust can be corrosive.

My mill is 2 post. the sawframe goes up and down fine with the 2 sleeves. the only reason for the 4 post would be to support the other 2 posts. There is no reason you need to connect all 4 posts together. Balance between the sawframe and engine is going to be your key design aspect. 

If you do make it perfectly balanced it should move real nice. But then you will probably need bearings on the mast to keep the sawframe from rocking causing waves. Some planned balance may be better. Leave one end heavier than the other and it will not want to rock.

sdboers

The cost isn't bad.  About $120 CAD for 2 rails and 4 bearing blocks - shipping included.  Although you can find the same things for WAAAAAYY more money than that!

What I'm hearing is - "Stop over thinking this.  Leave it telescoping on two posts and move on dude..."  :)

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

Joe Hillmann

Quote from: sdboers on November 05, 2018, 08:08:03 AM
The cost isn't bad.  About $120 CAD for 2 rails and 4 bearing blocks - shipping included.  Although you can find the same things for WAAAAAYY more money than that!

What I'm hearing is - "Stop over thinking this.  Leave it telescoping on two posts and move on dude..."  :)

Sean.
What good do you think those extra two rails will do? 
Mine is two sliders that are a very sloppy fit on two 2x2 posts.  I drilled several 5/8 holes into the sliders and welded a 1/2 nut over each hole.  Then I could put a bolt into each nut to take the play out.  Once I had the engine and battery and fuel tank on the head was back heavy and that took out all the play.  On some occasions when I raise the head up higher than I really should without the engine running it will get stuck and can't be lowered.  All I have to to is start it up and the vibration of the engine allows it to come down again.

sdboers

I guess in my head - my initial thinking was that 4 posts with sliders would keep the platform more level and help avoid any binding.  I also figured it would keep the whole unit more stable - less play.  It sounds more like I'd be causing the problem I'm trying to solve (not the first time I've done that in my life!) - and precisely the reason I'm posting here before marching off and building on my own.

I haven't heard a single person say it's a great idea, and I've heard plenty of folks point out valid reasons why it would be a concern.  I learned a long time ago that if everyone is giving you the same advice - they're all wrong.  errr...  I mean - they probably have a point.  :)

So - I think at this point I will keep the 4 posts for a nice solid cage - and only use the front two with sliders to support the head and platform itself.  Sounds like a 4 corner chain lift would also be overkill - perhaps better to stick with two on that as well.  Sometimes we get stuck on a notion in our head and need to be talked out of it.

Sean.
Random acts of kindness MUST outweigh random acts of violence each and every day. Make your mark today.

Crusarius

now just for fun here is another scenario.

I like the linear bearings. they make for super smooth movement and are typically pretty stout as long as they are sized appropriately. Put the linear bearings on the back 2 posts, run the chain to the front 2 posts. Now you get the stability of the linear bearings for up down and left right movement but the easy lift with the chains to the correct spot. The front posts would then act as lifting and rigidity for the entire carriage.

No sleeve or connection to the front posts just let it hang between them. The rear posts would be the guide. In fact if you did it this way you would only need a single chain in the center for lifting. you could actually mount the motor to the sawframe and not have to have long cables to power it.

another thought. use a winch for raise and lower. mount the winch where the battery tray would be between the rear posts. the run cable up to top of frame and back down to sawframe. Winch is still on frame next to battery so short power cables. This could also give you some ability to double the pull to slow the movement or get more torque. means you could get away with a $50 harbor freight winch. 

I miss having autocad at home otherwise I would do a quick sketch. Man I wish I thought about this stuff when I was designing my mill.

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