Napier Horizontal Band Saw repairs/rebuild

This adventure started over here but I figured a proper thread for this saw would be better (I'll leave those pics there):
Old horizontal band saws

As I said, I really didn't need another project, but it's here and the desire to see another overhead flat belt machine put back to work beside some modern CNC hardware has "forced" me to start working on this one.

It's temporarily outside until I can get some room made under a roof. The first thing I did was dig all of the chips and sludge out of the coolant pan/tank and scrape most of the dried sludge off of the rest of it. I found that they never put a drain plug anywhere on this saw (?) so I drilled and tapped a 3/4" NPT port right at the bottom corner of the tank and left it open so any water can drain out. I've left most of the grime on it and coated everything else with a good rust preventer we have. It sprays on thin and leaves a thick waxy coat behind. I'm trying to take care of it despite the elements.

I did find a serial number located on the front right corner of the table, #824


I also stripped all of the old weld-ment junk off of it, which was mostly stuff to gear down the motor to a manageable speed. The motor was kinda old but had major armature/bearing issues and was really hack-repaired on one side, so It was chunked and I have a couple other options to power it.

I moved the outer shaft bracket back to it's original position and stretched the shaft back out to it's original length. It had a nub on the end so I turned a piece to snuggly fit it, welded them together, and then turned the OD smooth. I had a 12" flat pulley too that I think will work for this application, though I'm still figuring out how to do it.


I did some math and found that to give a range of 50-275 feet per minute (our current band saws range), the input shaft with the 12" pulley will need to turn 33-183 RPM. A 2" motor pulley will be fine for the high speed, and I'm either going to use a 1 1/2HP DC servo motor/controller set we have on the shelf, or an old 1HP 3 phase motor with a VFD, to give the lower speed range. Mounting the motor will be easy as I have plenty of room to put it on a plate under the drive shaft, then I can make a simple enclosure to keep the belt and motor away from chips/coolant.

How to mount the 12" pulley is still still up in the air as it originally had a mechanical clutch with it that the operator could engage/disengage as well as having a trip to knock it out when the cut stroke is done. The easy path will be to just mount the pulley solid on the shaft and use a contactor and limit switch to turn on/off the motor. I'm also considering trying to replicate the old mechanical clutch though.
This is another saw with the original clutch.


I'm also having to figure out guards for this saw. Originally it had a drip pan that followed the blade around. It think this broken piece is where one end of it mounted.

I'll also need to make a new material stop and fix how it mounts as the lug is broken off, I'm thinking I'll leave that piece as a guide for the new rod and bolt on a new lug beside it.


This saw had none of the old coolant pump/lines left, but the lines will be easy to put back. It had a gear pump mounted under the drive shaft that was driven off of that shaft by a V-belt or chain. I'm going to be on the look-out for an old Brown & Sharpe gear pump to put back there, but I'll need to mount a separate motor to drive it since the saw will now have a varying speed.


There also used to be a ratcheting mechanism that would keep the arm up for you until you disengaged it with a handle. Part of it's still there but I'll need to replace the pawl and perhaps a spring to hold it out of the way when the saw is cutting.


Those are the main points I'll need to address. Get it complete, turning, and get it safe to work around. I'm not going to bother with paint right now as that can be done once it's earning it's keep inside.

This is a neat piece. I haven’t seen anything like it. Looking forward to you getting it back on line

This project is still awaiting some time to work on it (it's out of the weather in a container though), but a couple thoughts I had about it the other night:

In order to "sell" this machine to the other guys in our shop, it'll need more features than just being a cool old saw. That alone will keep it from going back to a line drive configuration and will require a bit of guarding to safely cover up the beautiful castings, BUT I'm ok with that as long as there are no permanent changes to the saw, and it keeps old iron active.

IMHO, at it's core this saw's a better and more rigid design than our current wonton-noodle MSC/Cosen horizontal saw, but in addition to that it will have a VFD for easier blade speed adjustment (step pulley on current saw), and I'm planning on bolting a roller rack to the infeed side to make moving stock through easier. This of course is all stuff we could also add to the MSC, but I can't make the casting thicker.

I'm also considering adding a little automation to the arm movement. It currently relies on a massive coil spring and adjusting knob to balance the arm, and there's evidence of some kind of ratchet and pawl mechanism that I assume was just to hold the arm up between cuts, but it's missing pieces. I don't want to make any permanent changes to the saw, but I'm thinking about bolting a jack-screw system in place of the ratchet mechanism that would incorporate a variable speed motor (DC or VFD) and a couple limit switches. You could then adjust the down-speed and when it bottoms out on a lower limit switch, have it return to an upper limit switch at the top of it's travel at a faster speed, and cut off the motors. Other than speeding up operation of the saw, this also enables all of the controls to be at a single panel, and I think it will be more responsive and reliable than our current saws simple hydraulic down-feed control, which still requires the operator to lift the arm between cuts.

It will be fairly simple to wire, and The motor and jack screw shouldn't take much room, but my only unknown at this point is how strong of a motor I'll need to lift the arm. I think I'll keep the coil spring system in place, and the jack screw creates mechanical advantage, so I don't THINK I'll need much of a motor, but I might see if I can measure how much down-force the arm presently generates and do some math.

I did find a couple old Brown & Sharpe gear pumps for the coolant and have the plumbing lined out. The only thing left is to figure out how to mount it's drive motor and get the right pulley ratio so I don't create too much pressure. I'm also planning on having a washdown hose plumbed to aid in clean-up, and when I add the guards for the blade, wheels, and pulleys, I'm going to try to improve the drip control around the arm. I had also thought about automating the arm with hydraulics and using the coolant pressure AS the hydraulic fluid, but I think it'll end up unnecessarily complicated.

One of the other projects I've picked up is completing a canibalized Brainard production mill (1880's?), which is also missing it's raised-lettering compartment door. With both it and this saw, I have catalog images that give a somewhat clear picture/concept of the writing and layout of the doors, so I'm considering making or having some patterns made to sand-cast replacement doors. I don't think there are any other mills around the same model as my Brainard, and It seems my saw and the one pictured on Vintage Machinery are the only one's remaining (according to the internet at least) and both are missing the door. The other saw is apparently on display at Greenfield Village, I imagine as a museum piece, so if I can get a pattern and casting made I'll make a second for that saw too.

Napier Saw Works; Metal Saw & Machine Co. - History | VintageMachinery.org

Vintage Machinery has the most information about the seemingly illusive Napier company. It looks like they were conceived to build steel cutting machines, starting with the more common power hack-saw, but they also seem to have developed the "continuous cutting hack saw," which soon became the modern day horizontal band saw. I haven't delved too far into the patents yet, but it looks like they pretty much invented the machine and promoted it over power hack saws for all of the reasons you can imagine (less moving parts, less vibration, smaller kerf, faster, etc. etc.)


This image shows the missing compartment door fairly well. At least well enough to recreate it IMO. The compartment is a combination coolant sump/chip box, so the door is just there to facilitate clearing out chips when needed. I might see about adding some kind of fitted screen basket in there to speed up chip removal. One corner of the box has a couple baffles so that chips can sink to the bottom of the box and coolant can spill into the corner to be sucked into the coolant pick-up. I think it would be prudent to add a screen over the end of the pick-up and save some wear to the gear pump.

In regards to the guards for this saw, I'm still considering how best to approach them. The minimal guarding it had when new really only helped to contain drips and nothing more. I could also do a simple box over everything, but it would make the machine much larger and make it harder to service, so somewhere between those two extremes is the goal. I'm thinking I'll make wheel covers similar to modern saws of a clam-shell style construction that can come off for blade changes and funnel chips and drips back to the cutting area, and then a simple box over the motors and belts, that could also serve as a tool/part shelf. With the necessary geometry around the blade and wheels, I'm thinking I'll draw it up in CAD and outsource having the pieces lasered out of some heavy gauge sheet metal, then weld them together with some supports and mounting brackets myself. The belt/pulley cover should be simple enough for me to cut and weld it from scratch. That one will also need easy access to clean out stray chips, coolant, and to keep the belts clean.

Found some great photos from the factory. Jake

http://emuseum.chs.org/emuseum/obje...7b26b6ee1fbddd9d7ef1e9c45ed438b8fb0f3db&idx=5

http://emuseum.chs.org/emuseum/obje...7b26b6ee1fbddd9d7ef1e9c45ed438b8fb0f3db&idx=6

Maltesehunter said:

Found some great photos from the factory. Jake

http://emuseum.chs.org/emuseum/obje...7b26b6ee1fbddd9d7ef1e9c45ed438b8fb0f3db&idx=5

http://emuseum.chs.org/emuseum/obje...7b26b6ee1fbddd9d7ef1e9c45ed438b8fb0f3db&idx=6

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Cool! Thanks for posting these! I wonder if the I-beam and sliding counterbalance was a later design or improvement over the coil spring on mine? Seems like it would be easier to fine tune than the spring.

I'm doing some research to get a better idea of when this saw was made, mainly so I can reproduce the cast iron door and use the apporpriate script on it.

The pictures from Maltesehunter in post #7 look like their source has been compromised somehow. Does anyone know more about them, specifically when they were taken and if it was at Napier (my assumption) or a customers shop?



I think this weighted arm design was a later development, due to the addition of electric motors as well, but it's on their 1920 patent here. VM also has a 1937 add showing the old spring-arm design with a different motor set-up. All of the early news articles show the spring arm design too, with the exception of their really early 1908 design where the band saw blade is pretty much floating in the air with no drums.

On edit: It looks like the 1920 patent has the spring arm function and no sliding counterbalance, but has a rod and turnbuckle for strength and support, so my current assumption is that the counterbalance was a later development and the I-beam design was just a way to prototype the machine before they made castings.

Man that saw must be really kind to it's bands, having the pulleys laid over like that. You seem to have so many irons in the fire Miles, I'm amazed you get anything done!

mattthemuppet said:

Man that saw must be really kind to it's bands, having the pulleys laid over like that. You seem to have so many irons in the fire Miles, I'm amazed you get anything done!

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The best projects cook low and slow . They just gotta quit finding me long enough to finish some.