I purchased a Sequoia 130 sawmill when I first got into sawyering, I will include a detailed review, I have a fabrication and machine shop so I have some insight into the technical aspects and details behind this sawmill. I'll start off by mentioning the positive attributes of this sawmill.
POSITIVE
1. Sequoia sawmill uses V-rollers on the ways that the head rig travels on. This gives it more surface area and lateral stability when you are milling and the angle iron is also less likely to be damaged or deformed when you put a log onto the mill.
2. Price, the sawmill are very affordable, around $5k.
3. Stainless vertical travel rails for elevation adjustment, when you adjust the elevation of the cut, the tube steel travels on stainless tube steel guide rails. If mild steel were used, a small amount of corrosion would make the head bind and rack and adjusting the elevation would be difficult.
NEGATIVE
1. Excessive Deflection under load, the bed is supported by 4in C-channel and includes 4 jacks on the corners for leveling. I asked Neil how much deflection I could expect on large logs, he claimed it was negligible. On larger oak logs, I was measuring about 5/16in of deflection. I ended up fabricating 6 jacks to support the carriage and this solved the issue.
2. Pillow block bearing are cheap Chinese make and inherently weak. The first 5 hours of milling resulted in 1 of the large pillow block bearings on the shaft of the band wheel cracking. Neil uses 1 & 7/16 which is an odd size as well. I called him and he sent 2 replacements, knowing that it likely would happen again. Also, there are grade 3 washers between the bolt and the square tubing that move in a slot to allow for alignment of the band wheel. The 3/8 bolt is tightened down, when the alignment is correct, to hold the band wheel in place. Unfortunately, the washer will deform over time and the band wheel will lose proper alignment. I fixed this by using (3) grade 8 washers which stop them from deforming and allowed the mill to hold alignment.
3. Through bolts in the pillow block bearing (movable side) are constantly being deformed. When you tension the blade it puts shear force from the square stock onto the 3/8 bolts that hold the pillow block bearing onto the tubing. This is the most serious flaw in the design of the sawmill. I have replaced several sets of through bolts as they became deformed, when this occurs the band wheel will not track properly and the cut will rise or dive and the blade will be thrown off the band wheel. Neil suggested that I rebuild the mill ever 10 hours as the bolts become deformed but this is obviously not very practical. To solve this problem he could have use a heavy linear bearing to take some of the load of the through bolts or he could have gone to 1/2in through bolts and a larger pillow block bearing.
4. Dogs are under built and easily bent.
Dogs are made from heavy 1/4in wall 2x2 tube steel but pivot on a 3/8 bolt which gets bent immediately when loading a large log. When the bolt is bent, the dog will allow the log to protrude into the travel area for the head rig and you will not be able to clear the log. Using a 5/8 or 3/4in grade 8 bolt would have prevented this but Neil uses 3/8 grade 3 hardware for most of the components on this mill. The cheap grade 3 bolts also strip out fairly frequently and have to be constantly replaced.
5. Adjustable blade guide goes out of square due to the cantilevered design.
The movable blade guide is supported on the exterior post of the head rig, its an entirely cantilevered design that's inherently weak and gets bent after using the mill in large hardwood logs. On some of the larger mills that Sequoia offers, they have an auxiliary vertical support that runs in conjunction from an overhead position. Also there is a fair amount of slop between the square tubing male & female on the square tubing so you will notice when you tighten the set screw down to secure the movable guide bearing that it will move 3-5 degrees. It will occasionally have to heated up and bent back to square when it gets to far out.
6. Blade tension is inconsistent.
Blade tension is set by turning a piece of all-thread on a handle to a notch marked in the steel. As the blade stretches with use you may have to adjust it past the pre-set notch. Also, I have had to rebuild the sawmill at least 4 or 5 times and each time requires me to bring the band wheels back into alignment which will change the relative position of where the blade needs to be tensioned. Also, the design of this mill does not allow for much tension due to the shear force acting on the 3/8 bolts that hold the pillow block bearings in place and the 1/8in of slop/play between the tube steel frames. I eventually made a copper shim and pressed it between the tube steel to make the sawmill deflect less during tensioning the blade.
7. Log clamps are inadequate and very light duty.
The original log clamps were made from 1/2 all thread or something similar, they lacked the power to push the log against the log to properly secure it. Also the arm that pivots was made from thin wall 5/8 or 3/4in tubing and would flex under load. I removed the original clamps and fabricated some heavy duty clamps from 2in heavy walled square tubing and coarse acme thread. This solved the problem.
8. Thin walled tubing and cheap grade 3 bolts/washers/nuts.
Most of the nuts, washers, bolts had to be replaced with grade 8 as they kept stripping. Some of the steel is only 1/8in thick and is threaded with a tap which strips quickly. Nuts must be welded onto the steel to allow for adjustment of the bearings without stripping the thin walled steel.
Overall, owning and running this sawmill has a huge learning experience, it taught me a lot about diagnosing issues/ problems and engineering a new fix to get back up and running. When I purchased the sawmill, Neil claimed it could mill about a 28in hardwood log. Even with every modification I made to the machine, the sawmill could never handle anything over 24in and cut accurately. In all reality I spent about as much time fixing & modifying the sawmill as I did cutting lumber.