Grob Bandsaw: two blade slots in table

[neilho]

I'd be interested to see the speedchanging setup - pulleys, belts, etc.

Mystery to me why the different blade lengths.

 

[86turbodsl]

I'll grab some photos and post em up. The saw looks totally factory to me.

 

[86turbodsl]

Ok, here's my NS18. Maybe you can spot some differences.

And for the record, this forum is a PITA to upload images to.

 

[Bill D]

Ok, here's my NS18. Maybe you can spot some differences.

And for the record, this forum is a PITA to upload images to.

I have not seen a proper manual for the small belt drive grob saws. How do the refer to the different belt shift positions. In other words what is first, second ..Eighth gear? Seems similar to trying to figure out a bicycle with a front and rear shifter pattern.
AFAIK Cars with overdrive only use the overdrive in top gear.
My Gravely tractor claims 8 speeds. four forward and then four in reverse
Bill D

 

[neilho]

Looks much the same as mine, except for the step pulley on the motor and its mate.

Same wheels, same drivetrain component positioning. Prob get more speeds with more steps in the pulleys, but a VFD sure seems easier.

 

[Bill D]

Wood to metal you need roughly ten to one reduction in blade speed. Not going to get that with a vfd. A VFD may be slow it enough for thin aluminum.
Bill D

 

[neilho]

Wood to metal you need roughly ten to one reduction in blade speed. Not going to get that with a vfd. A VFD may be slow it enough for thin aluminum.
Bill D

Bill,
So far as I know, Grob didn't publish a real manual for the NS18. There're exploded parts views with part numbers here at Grob with misc data, but no manuals.

Wandering a little here...for SN's before #3000, there was a 3 speed (with a 1/4 hp motor!), 5 speed (3/4 hp) and 10 speed (1hp) listed.

Can't find it quickly, but IIRC, top speed for the 3 speed was a fair amount lower than the 2050 sfm for the 10 speed. Could be that the lowest speed, a VFD and bimetal blades will make it usable for steel.

 

[86turbodsl]

Ok. My only use for this is steel. I just got it working on the vfd. Very smooth, but the blade tracks out on the edge of the wheels. I suspect the tires are shot. Anyone got a feel on how hard a tire change is? I know grob carries them for about 80 dollars. I had to weld up and machine the lower guide holder back straight. That seems fine, but with the blade tracking out, it's not even in the guides at the moment. As far as the speed, even at 60hz on the middle belt sheave, it's quite slow. the 3 speed was rated down to 50 sfm on slow speed. Perfect for cutting stainless exhaust tubing.

Edit: moved to slowest speed, even on 60hz on vfd, quite slow. I was able to cut through stainless tubing like it was butter with a bimetal saw blade. With a 1hp motor, this thing should be about unstoppable. Just need it tracking right.

 

[edwin dirnbeck]

A photo of the machine would be interesting, but labelled illustrations are better. Vintage Machinery has a Grob instruction book that shows that the slot pointing toward the face of the file or saw blade is for a feeding device and the one at 90 degrees to the direction of feed has holes for center pins for cutting circles of different diameters. See page 3.

http://vintagemachinery.org/pubs/2285/5680.pdf

As a bonus, I found that Grob made "open end" band saws. They used a 140 foot long narrow blade (that was not welded) that wrapped many times around top and bottom drums. It would cut for a while, then you stopped and quickly rewound the blade to the top drum and ran it again. It was an alternative to cutting a blade to pass it through an internal hole in the work, then welding the blade, doing the sawing and cutting the blade again. I thought that was an interesting idea.

http://vintagemachinery.org/pubs/2285/25799.pdf

Larry

I thought it was april fools day,when I read your post about a 140 foot LONG SAWBLADE. I still would not believe it if I didnt see the pictures.The catalogue says that the blade is wound helicaly (like thread on a spool),so how did the do this ? Did the upper and lower wheels (drums) move lengthwise?

 

[edwin dirnbeck]

Nice work on the miter gage and blade guides, I may borrow a couple of ideas, thanks.

The NS-18 (at least the older models, mine is from 1951), was originally set up to use a maximum 1/2" wide blade; this is evidenced by the cutting chart (replete with asbestos data), the welder capacity, and the bronze blade guides came in a max 1/2" deep size.

One of the most interesting things about this saw is the trunnion design, I don't know if newer Grobs use this design, the 4v shown in another post has a conventional cast trunnion. As shown in the pictures, a big ground plate sector sits on two big flanged beveled tooling pins, and is restrained and clamped by two clamping pins actuated by two cam levers on the back (the center cam-lever is for the blade holder asm). This also has the compound axes.
This is by far the most stable, easiest to move, and best-balanced bandsaw table I've had, either on a small or larger saw (14,15" wood saws, 21" Delta metal saw, 24" northfield wood saw, standard DoAll). The (big 24x24) table is a hollow casting, and 1/8" plate used on everything. Much was apparently jigged together and welded, since the only adjustment on the original blade-guides is front-back and they are perfectly aligned with top and bottom wheels. On this saw, I put a VFD on it, fixed up the welder (they're pretty simple mouse-trap affairs), replaced the bearings (wheels and jackshaft), belts, scabbed on the smallest worn-out pully on the jack-shaft pully cluster (wasn't needed with the VFD), brushed on a coat of Rustoleum Pro Smoke Gray. There's a ratcheting "mechanical power feed" with adjustable weights actuated by the foot pedal, and slot bar mechanism (just played with it, never used it). It's sort of therapeutic and hypnotic watching all those big silent pulleys and belts goin' round and round. CheersView attachment 368257
View attachment 368252View attachment 368253View attachment 368254View attachment 368256

Beautiful pictures,I hate doalls trunion design. I hate trunions period. But Grobs design is the best that I have seen.

 

[Jim Moser]

I would like to add to this thread but can’t post pictures simply.
Oh Well

 

[Peter S]

We cut 3" out of the 144" ones i had made at Detroit Bandsaw and it fit perfect right in the middle of the travel range of the adjuster. What would you want to see on this one? I can post photos.

Hi, I think a new blade would be made as long as possible (i.e. near the max. travel) to allow for repeated shortening? Every time you re-weld, you are supposed to cut a bit off the ends. That's if your work involves breaking the weld to fit the blade through a hole and then re-weld.

Also, if you haven't welded blades for a while, you might have to shorten and re-weld several times to get a good one

It's a long time since I did this sort of work, but that's what I recall.

 

[neilho]

FWIW, I used the Grob tires on my NS18. No adhesive, no shaping afterwards, they've worked well for almost 25 years.

 

[dkmc]

Ok. My only use for this is steel. I just got it working on the vfd. Very smooth, but the blade tracks out on the edge of the wheels. I suspect the tires are shot. Anyone got a feel on how hard a tire change is? I know grob carries them for about 80 dollars. I had to weld up and machine the lower guide holder back straight. That seems fine, but with the blade tracking out, it's not even in the guides at the moment. As far as the speed, even at 60hz on the middle belt sheave, it's quite slow. the 3 speed was rated down to 50 sfm on slow speed. Perfect for cutting stainless exhaust tubing.

Edit: moved to slowest speed, even on 60hz on vfd, quite slow. I was able to cut through stainless tubing like it was butter with a bimetal saw blade. With a 1hp motor, this thing should be about unstoppable. Just need it tracking right.

I put the blue urethane tires from Ebay on mine. You might start off easy, but if you want to get them on, you'll end up needing to get fairly aggressive. Not sure if soaking in hot water (the tires that is) helps much, but I found copious use of expletives and outright physical threats to the machine to be most effective in accomplishing the goal. I did it with the wheels on the saw, as there didn't seem to be any safe way to hold them while off the saw without risking damage to the aluminum.

 

[86turbodsl]

What tracking adjustment? i don't see anything on it.

Edit: Never noticed that teeny little thumbscrew before. Ok, i have the top wheel tracking nicely on the crown, the blade is running in the guides, the lower wheel, it tracks out on the edge still. I probably need a lower tire at least. I can shove it into the bottom of the guides when cutting, but the blade works out to middle when done cutting. It's good enough to keep it in the guides for now, i can get my 2 exhaust jobs done. That thing is SLOW on 60hz slowest sheaves.

 

[neilho]

Car2's advice is on the money, and the the Grobs of that era do have a crown machined into the (cast iron) wheel.

If the lower wheel bearings are sloppy, the wheel could tip with the result that the blade would track at the outside. And if the lower blade guide were out of whack, the blade would track to the outside. And if...

Lots of ways for the blade to track incorrectly. Unless the lower tire is obviously no longer crowned, or cracked, seems like something else is the culprit.

I like to check any changes that could affect tracking by rolling the wheels by hand. There was the case of a new blade being ruined by starting the machine right up after a blade change, just assuming it would track correctly the first time. DAMHIKT

 

[86turbodsl]

Ok, i pulled tension off the blade, the upper wheel is nicely crowned to the center, the bottom wheel is a mess, wavy if you will. The bottom wheel has about 1/8" play at the rim, checking like a wheel bearing on a car. I'm thinking it needs a lower tire and bearings.