Horsepower Requirements for a Widebelt Sander
From contributor S:
I don't see how the number of users affects the HP. What is considered a large amount of stock to remove? .3 of a mm? That is less than 1/64 of an inch.
My point is, what is the use of a two head machine if you end up doing multi-passes all the time? Essentially you are wasting the second belt and may as well elevate it until you have made the bulk of your passes on the coarser belt to get within range. I want enough power to remove minor tear out from solid wood left by the planer and to flush solid wood panels and 5 piece doors.
I remember hearing a formula years ago that stated 1 HP for every 2 inches. That means the machine I am looking at is slightly underpowered, but the other one is well over the required HP. I consider the machine I have chosen to be more robust with a larger contact drum - 190mm versus 140. So the fact that the lighter machine is offering more power is a bit confusing.
From contributor L:
I used a Timesaver that had a 25HP front head and a 20HP rear head. You could let the power meter go up to about 30% before the machine would start to feel the load. We would usually have a 100 on the front and a 150 on the back. We used the platen on the back belt. We could take 1/32 of an inch off of a piece that was about half the width of the belt (37" belt, 16" piece).
The reason the HP affects the amount of people who can use it is simple. More HP will allow you to use the machine quicker. You can run the conveyor at a faster speed and take off more per pass. This usually meant that if you had to do a front and back pass it would take two passes. One for each side. Then the machine would be open for the next person to use. If you had to do 4 passes that person would have to wait longer, slowing production down. Like I said, if you are a smaller shop it doesn't make too much of a difference. But if you have a crew of 10 or 20 it can make a world of difference.
From contributor J:
I'm no widebelt expert, but 20 and 15 should be fine for finish sanding. One thing I like about my SCMI is that it has a pneumatic activation for the heads. So you can flip any element (first drum, second drum, platen) up with a switch on the control panel. If you have to rough something down, there is no fussing with the internals.
From contributor D:
Thought I'd weigh in here too for the bigger is better argument. I build custom wood doors and sanded thousands of them with a single head 27hp 43 x 60 belt Chinese machine. It worked fine. I thought. Then a couple years ago we got a new three head 53 x 104 belt and the difference is night and day. The extra grit hitting the stock takes it down without choking up and leaves virtually no hand sanding. The adjustments are more precise, it runs cleaner and overall does a better job, and it saves hand labor. The other one periodically had to be tuned up and dialed in, the eccentric cam height adjustment held with a set screw got eaten up, the platen graphite had to be changed often, bearings on the feed belts burned up as did brake pads, and various electrical relays often malfunctioned due to running dirty and fine dust getting in them. I could go on. I thought all this was normal.
From contributor B:
If you want solid wood to run in one pass, you need a planer/sander. Now the sanding heads are doing what their name implies, sanding. Removing 010 with a 120 grit belt is tough; .015 is even tougher. At some point the HP is going to outlive your sanding belt. Smaller lighter import machines come with more HP; it sells the product.
From contributor K:
We are a 4 man shop with a Butfering 43 x 75 with a 20hp and 15hp respectively. We use 120x and 180x 3m purple heavyweight belts and take .3mm per pass.
If you're sanding wood blanks, panels off the planer, doors, etc., then 20/15 hp is fine at .3mm per pass.
Our machine has a solid steel (no rubber) first head which is a double edged sword because if you come in too hot, you will burn up the belts like there's no tomorrow, but the accuracy of a solid steel initial contact roller is amazingly superior to rubber heads and you don't have to spend thousands on a new rubber head when bad things happen.
I finally got smart (after 9 years of burning belts) and bought a quality digital caliper which stays at the machine so every run can be calibrated perfectly to the material instead of relying on the machine's calibrating unit, which has eliminated burning belts.
We also found that the 3m purple heavyweight belts work the best (we have tried everyone's), but they cost 100 bucks plus and you have to buy 5 at a time for each grit you use.
Rubber contact drums are easier on belts, so you can run the cheapies as far as belts go, but you sacrifice absolute flatness in time.
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