Bandsaw Log Sled

Work Holding Larger Logs on the Bandsaw

Since I own a lathe that can handle huge logs (Stubby) we are often confronted with the challenge of preparing large blanks. This usually dictates the use of a chainsaw and other means of wrestling the wood into a turn-able shape. Preparing large wood for me is the unpleasant part of turning.

While processing the large aspen logs for the lamps [previous posts] I broke a 3/4-3 TPI bandsaw blade. This isn't the first time! So at $30 a pop, I decided to pay more attention to the cause. Note: I did find a blade on Amazon for $16 that I am testing.

I decided that the reason the blade broke is that I was free-hand cross-cutting the ends of logs. Along with being an unsafe method of preparing wood, it is prone to twisting/binding the blade which leads to breakage.

So I proceeded to find a simple and better way to:
-Feed logs for cross-cutting on the bandsaw
-Weld bandsaw blades

Sled Design & Fabrication

After lots of internet research, I settled on a simple sled for the bandsaw that features two moveable horizontal stops with one edge cut at a 45. Most of the sleds I reviewed had a fixed V to hold the log. Logs generally are not the same diameter from one end to the other.

To allow a level of adjustment I milled slots into the sled and anchored the stops with carriage bolts. The stops are adjusted to fit the profile of the log and are then secured with a belt and an old ratcheting snowboard clasp. I knew there was a reason to keep that clasp.

There is a tenon screwed to the bottom of the sled that rides in the miter slot to keep the log square to the blade.

Now a clean straight cut

The miter slot keeps the log straight

Adjustable stops that you can align to the log

nice controlled clean cut

firmly attached and aligned to the miter slot

locked and loaded

Conclusions

Certainly, square log-ends can be achieved by cutting the log square when harvesting but most of the time the pre-cut logs I get from the trash are not cut straight. There are also times when the noise of the chainsaw is objectionable in the neighborhood.
You can also mount the log on the lathe and part away the angle if you can get it mounted straight and get enough bite from the spur center.
The band saw sled is just another option for processing logs.

I will employ a separate post sharing my experience with welding bandsaw blades

Enjoy and please comment;

Don

Welding Bandsaw Blades

 Repairing Broken Bandsaw Blades

Braking a bandsaw blade is one of the most frustrating and costly events that you can experience while preparing logs for woodturning.

While engaged in a large lamp project I again broke a 3/4-3tpi blade which costs $35.

Along with making a jig to better feed the log into my bandsaw, I embarked on a project to weld broken blades.

I watched every YouTube video that I could find on methods and jigs for welding blades and settled on a design and method.

The jig needs these features:

• A long base that allows clamping the blade in place 
• An open area where the seam can be welded
• A reference edge that will register the top edge of the blade
• A reference stop below the seam that holds the seam together while welding

The Base

Many of the jigs used a piece of angle iron for the base. This material is problematic as the inside corner has a radius that prevents a positive reference point for the top of the blade. The blade will tend to ride up this radius unless it is removed or other fixed reference points are provided.

I had a piece of stock in my bin that had tightly bent 90s that I used for the base. I think I go this either at a big box store or at McMaster Carr. Although I ended up milling the corners of this material [just for finese] the first blade I welded fine without it. 

A square hole was cut in the upper center of the base and the bent edge was cut away to facilitate access to the edge of the blade while welding. I found that at the weld the upper edge had a tendency not to properly wick leaving a void when it is touching the base. 

A small plate is welded on the bottom of the base to hold a "backing bolt". The plate is tapped to accept a section of 1/4-20 bolt which has one end grout to a point. This bolt is used to put pressure on the back of the scarf joint and hold it tight to the upper blade section while welding. The bolt is adjusted to touch the lower section of the blade at the scarf joint and uses a wing nut to lock it in place.

Simple Clamping

I clamped the blade to the base with hand spring clamps. Most designs I looked at had bolts or over-center latches to hold the blade. Spring clamps require no fabrication, worked fine, are simpler, and act less as a heat sync. 

Preparing the Joint

The ends at the break have to be ground to provide a scarf joint. It's important that the resulting weld be very flat otherwise it can damage the bandsaw track and/or cause failure. The conventional thinking is that the scarf joint should be ground at 20 degrees with straight and square edges. Seems my jig ended up being 16.

I cut a slot into a sled to facilitate grinding this angle. This sled worked but I found that I need a better way to clamp and hold the blade while grinding. It was difficult to hold the large blade still while moving the sled. That's a planned enhancement that will precede the next weld attempt.

Welding Method

The popular methods included brazing, silver solder, arc, and tig welding. I judged that arc and tig welding would require skills well outside of my abilities and would result in a joint that was more difficult to grind. I tried silver solder without good results. It did not want to flow into the joint. I later realized that I was not getting the joint hot enough so I will try that silver solder again next time.

I ended up successfully brazing the joint with a brazing rod and LOTS of flux.

I purchased some silver solder and flux to perform the weld but ended up using a brazing rod and the flux instead. I used a map torch as a heat source.

Welding

I flailed on the first band repair but finally realized that the problem was that I was not getting the blade hot enough. The process that worked the best was:

• Clean all surfaces of the blade with an 80-grit wheel.
• Clean surfaces with acetone
• Clamp one end of the blade hanging over the edge of the base with the surface to be welded facing upward
• Heat the scarf area to red hot with flux applied
• Tin the blade with flux and brazing rod by applying the rod with the heat until it flows naturally across the joint
• Repeat tining the other side of the scarf joint
• Clamp the blade on the base with the scarf joint aligned but the blade surface not overlapping.  Slide the blade left-right until the combined thickness is the same as the blade.
• Apply heat to the joint until both the top and bottom are cherry red. Use plenty of flux. When the joint is fully red touch the solder onto the surface and into the flame. It should melt and suck into the joint. The key is to allow enough solder to flow into the joint to make it strong but not so much that the joint is too thick.
• After cooling grind the joint flat on both sides

Annealing

This is important. Since the repaired area has been hardened from the welding temperature the metal at and around the joint needs to be annealed so it is not brittle and prone to breakage.

This is the method I use:

• Grind the surface 3-4 inches from the joint so that it is bright metal. Removing oxidation facilitates seeing the subtle color transition.
• Use a butane torch on low heat or alternately a map torch with a careful and intermittent application of the flame to the blade.
• Slowly heat the blade to a straw color about 3 inches away from the joint. Then move the torch up the blade toward the joint. This should cause the straw-colored area to move to the joint. 
• The straw color transition is subtle and quick. It's easy to overheat the metal and when you do it will turn blue. The blue color means you have gone too far and potentially hardened the metal. 
• When the straw color encompasses the joint stop, and allow the blade cool. DO NOT QUENCH!

Results

The first blade I welded turned out too thick. On this blade, I did not tin the joint and tried a suggested method where the solder was placed in the joint before heating. I later realized I did not allow the joint to heat up enough and also suspected that the C clamps were acting as a heat sync. In this attempt, there was no backing bolt in the base. 

Too much overlap at the joint makes it too thick.

Good coverage but to thick

The silver solder attempt did not work.

The second blade welded easily. I waited until the joint was fully cherry red, used a lot of flux, and has spring clamps vs C clamps. In this attempt, there is a tiny discontinuity visible at the joint and on the top edge. I was surprised that this tiny notch creates a ticking noise in operation.

Mounted on the saw, good connection, just a tad too thick. Runs with a small tick.

Enjoy and please comment.

Don