1940s Marvel Series 8 Bandsaw - Bogs down constantly?

[animal12]

I bought a bandsaw way way back that was made from a kit . A Gilliom kit . Ya bought the hardware & plans & built a tool , pretty cool .The guy did a great job building it but said it never cut right . I could see a pretty new band saw in his shop. I looked the saw over & In the most polite voice I had I told the guy that he had the blade on upside down , he went & looked at it & shook his head . He was askin $ 20.00 & I offered him more but he wouldn't take it . He did have the blade on properly on his new saw . In the years I have had that saw it has probably cut 100 + pinewood derby cars with Cub Scouts . Yep backwards/upside down blade's do happen .
animal

 

[memphisjed]

Out of curiosity- is it a machine specific speed chart or generic blade speed chart (similar numbers that are on blade box)?
1.25 horse per inch thickness to get cut speeds by blade manufactures.

 

[Ries]

I know the tiny horse and a half is stock on that vintage of Marvels, so it "should" work, but it still seems awfully wimpy to me. I long ago upgraded my little 4x6 horizontals to 1hp motors, and my big 10x16 bandsaw is at least 2 or 3 hp.
Also, buy a new blade. "Seems sharp" could still mean dull. Bandsaw blades are consumables, they wear out. I would definitely be running a lower tooth count Starrett or Lenox bimetal blade if I was cutting 4" plate.

 

[Dope]

Out of curiosity- is it a machine specific speed chart or generic blade speed chart (similar numbers that are on blade box)?
1.25 horse per inch thickness to get cut speeds by blade manufactures.

This is straight out of Marvel's manual for this machine, based on material and blade tooth count. Unless oldschool manufacturers massively overrated their capabilities? Honestly, I've generally found the opposite to be true so I'd be surprised.

 

[Dope]

I bought a bandsaw way way back that was made from a kit . A Gilliom kit . Ya bought the hardware & plans & built a tool , pretty cool .The guy did a great job building it but said it never cut right . I could see a pretty new band saw in his shop. I looked the saw over & In the most polite voice I had I told the guy that he had the blade on upside down , he went & looked at it & shook his head . He was askin $ 20.00 & I offered him more but he wouldn't take it . He did have the blade on properly on his new saw . In the years I have had that saw it has probably cut 100 + pinewood derby cars with Cub Scouts . Yep backwards/upside down blade's do happen .
animal

I believe it, last horizontal saw I bought the guy admitted that his apprentice had put the blade on backwards. It had cut through one piece of 2" solid round before they noticed, I can only imagine how long it took. Made a shockingly nice cut but the blade was duller than a 2x4.

 

[EmGo]

I believe it, last horizontal saw I bought the guy admitted that his apprentice had put the blade on backwards. It had cut through one piece of 2" solid round before they noticed, Made a shockingly nice cut but the blade was duller than a 2x4.

Hey, there's guys here all the time talking about cnmg inserts for little lathes and aluminum. Same thing. Negative rake is negative rake ...

 

[john.k]

The boat guy next to my shop was having trouble with his crappy saw .....blade was on backwards .....so I reversed it for him........he cut his finger off............maybe I should have told him what I did.............This guy used to do masses of work,and refused to buy decent tools or machines ......one time I sharpened his drill bits ,and then I had to blunt them all again.

 

[SeeFair]

as you engage the blade in a cut it starts rhythmically bogging down and speeding up - over and over.

Does the rhythm (frequency) change with gearbox setting? If it does, perhaps it's not the motor.

 

[john.k]

Used to be common to put a carbide circular saw blade on backwards to saw ally sheet cleanly.

 

[JohnMartin]

Used to be common to put a carbide circular saw blade on backwards to saw ally sheet cleanly.

Steel blades for sure, but carbide? Given carbide’s lack of tensile strength, I’d think that this would cause it to chip, badly.

 

[Superbowl]

I have used circular saw blades on backwards many times, both carbide and steel, for cutting wood. Slow but gives a very smooth cut. Never tried it on aluminum.

 

[Dope]

UPDATE TIME

So after a bit of holiday delay I got back to playing with this saw. I never really found any smoking guns so I reassembled the machine. I DID find something interesting while doing so. There is a 3-position flat belt/conehead configuration under the bed of the machine that I forgot about. I noticed that the belt felt a little loose. I also tried test cuts with the belt in different positions and it would throw the belt at any position other than the middle one. After some trial-and-error tightening (more difficult than I thought, going a little too tight would bind the whole system up somehow), I got it squared away decently enough and VOILA, there is no more bog problem.

My theory on the subject is that the belt may have been slipping momentarily under a heavy load. The power feed would keep pushing the workpiece into the blade briefly, causing a bog as the machine has to suddenly "catch up". This would just happen over and over again, causing a rhythmic cycle.

Doing a few minutes of testing last night, I was able to double the feed rate without even using coolant. No bogs at all, amazing!

 

[Rob F.]

Interesting, do you know where the serial # is? All of the data stickers on the machine are wiped out but there might be one stamped somewhere.

When I got my #8 I asked marvel about where to find the serial #, they said it is stamped on top of the table in the front right corner, right above where the feed handcrank & power feed gear is.
They told me that pre 1922 they did not use serial #s. Mine with a 1917 patent date is between 1917 and 1922.

 

[Dope]

When I got my #8 I asked marvel about where to find the serial #, they said it is stamped on top of the table in the front right corner, right above where the feed handcrank & power feed gear is.
They told me that pre 1922 they did not use serial #s. Mine with a 1917 patent date is between 1917 and 1922.

Oh I forgot to do this. Good call on the location, I never would have found it - it was completely encrusted. It is 812714. I did some googling but couldn't really find any age info pertaining to this, it seems most reference data is in the 4- or 5-digit serial # range. (30s and 40s). So this may in fact be a lot newer, unless they switched up the serial numbering at some point.

 

[Rob F.]

Marvel will tell you its age.

 

[neilho]

Depending on its age, the speed chart may not be for bimetal blades.

 

[TS3 Saws]

Marvel 8M8 Serial number 812702 was installed on 1/25/1978 - so you-re only 12 machines later than that.

Oh I forgot to do this. Good call on the location, I never would have found it - it was completely encrusted. It is 812714. I did some googling but couldn't really find any age info pertaining to this, it seems most reference data is in the 4- or 5-digit serial # range. (30s and 40s). So this may in fact be a lot newer, unless they switched up the serial numbering at some point.

Machine 812702 was installed 1/1977 - so your machine is most likely a 1977 early to mid year build.