Everett's Sawmill Build

JEverettM · July 19, 2019, 03:51:14 PM

Hi All,

I'm new around the forum but have been lurking for a while.

I am working on a manual sawmill design and thought I would start a thread to share progress.

The broad strokes are that it is intended to cut up to 36" wide on a roughly 20' bed.

The carriage is mostly HSS4x2x1/4 tube. The saw beam is HSS6x2x3/16 tubing. The trailer is C8x11.5 structural channel.

Band wheels are 18.75" for a 1 1/4" band and will be driven by a Honda GX630 (~20HP). I'm planning to use a roller chain style lift mechanism.

Planning to tension the blade with a bolt and a die spring with a known load rate. The drive belt will be tensioned with an idler that will be engaged manually.

The carriage will have v-groove casters on an angle iron track.

Log holding will be what I'm calling a sliding "jam-type" dog. I may or may not include some other alternate dog methods.

Other features shown are squaring stops, log ramps, a winch post, sliding wedges, and a movable toeboard that uses a scissor jack.

Everything will start out manual, but I'm trying to keep future automation and extension in mind.

I happen to have access to a large plasma table, so I'm taking advantage of the ability to cut steel plate to pretty much any shape I want.

Here's some pics of the design as it stands right now. Hoping to order steel in the next few weeks and get busy!

I can post more pictures as needed, but I didn't want to flood the first post with too many.

I'm hoping for questions, criticism, and suggestions, so don't be shy!

Hilltop366 · July 19, 2019, 04:59:00 PM

Welcome JEverettM.

I always enjoy watching a build, thanks for sharing.

RAYAR · July 19, 2019, 10:25:26 PM

Welcome Everett

Have fun building your mill. Some of these self built mills are well designed and great pieces of machinery. My mill is a local shop built mill about 13 to 14 years ago. I bought it just over a year ago and have been fabricating and adding parts to it. This evening, I just added two log dawging stations and an additional log back stop to handle short logs.

Ray

kelLOGg · July 20, 2019, 05:42:27 AM

I admire the skill you mill builders have to build-your-own. Here are my comments based my modified manual mill.
1) if you're sawing 36" wide (log size or lumber) use larger bandwheels. Smaller wheels cause a lot of band flexing due slower sawing in wide material and flexing shortens band life.
2)it looks like a manual winch for loading/turning. I think you'll need more than that for 36" and 20'

Just my 2¢

ktm250rider · July 22, 2019, 11:08:03 AM

make sure you have clearance between your blade guards and all your support jacks. I have to remove the handle on mine to clear when cutting down to 1 inch.

Hilltop366 · July 22, 2019, 11:15:13 AM

i will add that keeping shafts as short as possible and pulleys as close to bearings as possible will significantly reduce stress on shafts and bearings.

Crusarius · July 22, 2019, 12:20:52 PM

Quote from: ktm250rider on July 22, 2019, 11:08:03 AM
make sure you have clearance between your blade guards and all your support jacks. I have to remove the handle on mine to clear when cutting down to 1 inch.

I agree with this. I have 1 jack that doesn't quite clear. I have to open the guard to clear it.

This is probably a non issue but just to let you know C-channel can be strong but it allows quite a bit of twist. The good news is with proper support jacks that won't matter but depending on how bad it becomes it may be an issue when dragging it down the road.

Oh yea, also make sure you have some type of wiper on your tracks. otherwise the pitch and sawdust WILL build up and cause issues.

Keep us updated. We all love pics. Looking forward to another build.

Woodpecker52 · July 22, 2019, 01:01:44 PM

Everret, check out on sawmill exchange listing #18865 EZ Boardwalk Jr. in Iowa Price $4,650. Just saying!

JEverettM · July 23, 2019, 03:56:03 PM

@Rayar I've been following along as you make improvements. Great stuff.

@kelLOGg From what I've been able to glean online, it seems like band wheel size is related most directly to band thickness. So, the thicker the band, the bigger the wheel... otherwise the tight radius of the wheel will fatigue the band and cause either cracks or early replacement. Is that a fair assessment?

@Hilltop366 I'm trying to keep the band wheel as close as possible to the bearing, but the drive wheel will be spaced back a good bit. I've heard tha--though its best to keep the band wheel close to the bearings (when it is cantilevered beyond them)--it can be good to space out the bearings as far as possible. Do you think that matters? Is there some kind of minimum distance that should be maintained between bearings?

@ktm250rider One benefit of having a 3D model is that it should help with identifying interferences. Even so, some of the tolerances on this thing are pretty tight. Finger's crossed I don't miss anything too obvious. Thanks for the head's up.

@Crusarius Tube would be much better than channel for torsion, but it can be more than 4x's the cost per pound! I'm tying the channels together with crossbunks that are made of tube, plus plate as a riser. They should be fairly stiff. The jacks will be placed at opposite ends of a crossbunk, so I'm hoping the jack placement will keep the channels from rolling too much during loading. What about racking? Is racking an issue with these mills? Should I plan to add some horizontal cross-bracing?

Hilltop366 · July 23, 2019, 04:07:48 PM

Quote from: JEverettM on July 23, 2019, 03:56:03 PM@Hilltop366 I'm trying to keep the band wheel as close as possible to the bearing, but the drive wheel will be spaced back a good bit. I've heard tha--though its best to keep the band wheel close to the bearings (when it is cantilevered beyond them)--it can be good to space out the bearings as far as possible. Do you think that matters? Is there some kind of minimum distance that should be maintained between bearings?

Lots of variables, shaft size, shaft material, bearing type and rating.

I think I see what you are saying about spacing, like standing up with your legs spread apart a bit verses together for stability.

Crusarius · July 23, 2019, 04:09:28 PM

Quote from: JEverettM on July 23, 2019, 03:56:03 PMIs there some kind of minimum distance that should be maintained between bearings?

The further apart the more fine the adjustment can be if you are using a screw. If you have a big enough shaft, the bearing location is not as critical. However the less the shaft is spanning the better.

Quote from: JEverettM on July 23, 2019, 03:56:03 PMIs racking an issue with these mills? Should I plan to add some horizontal cross-bracing?

Racking can be an issue if you do not have sufficient support from your jacks. The only time racking really is a concern is dragging the mill around. I originally placed my jacks at the ends of the bunks only to find out that raising and lowering the jack the handles hit the bunks. That really sucks! So I will not make that mistake again.

Keep in mind your jack handle location, and the radius of the handle along with clearance of your band to the top of the jacks. One of my jacks ended up a 1/4" higher than the rest and the guard hits it on my last cut. I am not sure how I am going to fix that yet. But I cannot tolerate it. I usually end up having to open the guard on the last cut to get past the jack.

bwstout · July 23, 2019, 04:26:32 PM

I would think about a set of bunks somewhere close to you dawgs that were close, there will be time you may want to saw something that is less that 3'. I use my mill a lot to cut bowl blanks but I can cut 16' logs too. That was the first reason to build so I would not have saw them with a chain saw and the mill works good for this with the bunks in the middle about 16" apart. but certainly your call on this.

Crusarius · July 23, 2019, 04:42:32 PM

I agree. I made a mistake and made my backstops 3' apart. The first 3 should have been within 16" or maybe the first 2 within 12" of each other. If I had 2 backstops close enough 1 clamp would be sufficient. But I screwed up and with my rotating backstops I did not make it work right.

Hilltop366 · July 23, 2019, 05:06:07 PM

On band mills it looks like the largest load to is in between the bearing and the band wheel, I think this is the area that would need the closest spacing as there is lots of side load from the band blade tensioning.

The increased leverage of a larger band wheel size will also make a difference.

To me it looks like the home built mills that seem to have the most difficulty with consistent tracking have one or more of the following issues:

shafts that are too small
shafts that are too soft
too much extension beyond the bearings
too much space in between bearings
frame for band wheels flexing

I guess a frame with a bearing on each side of the band wheel would remove or reduce these issues.

RAYAR · July 24, 2019, 12:40:40 AM

Use as large of a shaft as your band wheels permit. Too small of a shaft is a future area of failure too soon, possibly catrastically. Since there are tremendous forces exerted on these shafts when the band is tensioned and running, the smaller the shaft and further apart the bearings, the more flex is introduced on the section of shaft between the bearings as the bearing next to the band wheel is acting as a fulcrum to create outward flexing of the shafts. This will also lead to tracking problems changing and possibly difficult to figure out why it's happening. The shafts should also be of a type to withstand heavy side loading with minimal to no flexing under pressures being applied.

Something to keep in mind when designing your set-up.

Ray

kelLOGg · July 24, 2019, 05:46:51 AM

Quote from: JEverettM on July 23, 2019, 03:56:03 PM
@kelLOGg From what I've been able to glean online, it seems like band wheel size is related most directly to band thickness. So, the thicker the band, the bigger the wheel... otherwise the tight radius of the wheel will fatigue the band and cause either cracks or early replacement. Is that a fair assessment?

In general that is a fair assessment but since you will be sawing up to 36" wide and that will be slow sawing requiring more band flexing. I guess there are 2 solutions: 1) more HP to saw faster or 2) larger band wheel. You didn't mention HP so I suggested #2.
Those with wide saws will have a lot to contribute on this and educate us both.
Bob

JEverettM · August 15, 2019, 12:17:05 PM

Progress comes in spurts.

Looking to have all my steel cut in the next couple of weeks, but I'm still waiting for some to be delivered.

This week I'm cutting raw material to length. Borrowing time on Behringer HBP Automatic Horizontal Band Saw. Its a pretty slick machine, especially when cutting multiples.

I also nested the parts and created the CNC programs for the sheet steel parts:

kelLOGg · August 18, 2019, 07:58:26 PM

:oOMG that's amazing! You must one heckuva workshop.

JEverettM · August 20, 2019, 09:19:38 AM

@kelLOGg I am just lucky enough to be able to borrow some machine time on the shop floor where I work. Though I am grateful to have it, my personal shop would rank somewhere between average to unimpressive.

Crusarius · August 20, 2019, 09:22:50 AM

laser cutter and cnc plasma tables are soooo nice.

Hoopty5.0 · August 20, 2019, 10:36:03 AM

That's impressive!

ktm250rider · August 26, 2019, 09:52:10 AM

That's cheating!

ssn vet · August 26, 2019, 11:59:34 AM

Looks like a solid design and detailed model.

What software package did you model it in?

JEverettM · August 26, 2019, 12:45:32 PM

@ssn vet I'm using Inventor for the 3D model and Hypertherm ProNest for the plasma nest and CNC code. I also used AutoCAD 2D a fair bit for quick sketches and to manipulate the DXF files for the plasma work.

I see that you've got access to SolidWorks. I'd be happy to share files with you if there's anything you'd like more detail on. Inventor can export to SAT, STL, and STEP, among other file types.

ssn vet · August 26, 2019, 01:20:25 PM

thanks for the reply.... I have access Solid Works 2019 and Inventor 2013.

I'd really appreciate the opportunity to study your models.

I'm working on my own design, and have quite a bit modeled already, but could really benefit from seeing how you did the toe adjustments on the wheels and the tensioning mechanism.

I'm tailoring my design to the components I have managed to dumpster dive, but I don't have an actual mill to study, so I'm making up more design elements than I'm comfortable with.