SAW FOR CUTTING COUPONS

Date 04-25-2007 20:23

What I use here at work is an old Marvel No.8...this one was mfg'd back in the late 40's early 50's. I would love to have a nickle for all the cuts that have been made on that saw. Still cuts true after all of these years. Slices through a one inch thick coupon in just a few minutes on autofeed.

By aevald

Date 04-25-2007 21:09

Hello John, would that be one of the ones that is oriented vertically, the head will tilt 45 degrees either direction, the table and vises are fixed, the head advances into the material to be cut and the auto feed portion of the saw uses a sliding weight that is friction driven off of the saw drive to adjust cutting pressure? If that's the one, they are definitely a great piece of machinery, simplicity and functionality. I could see where it would be a great saw for cutting test pieces. I use a DoAll horizontal saw and have a few special fixtures that I use when I cut coupons. If I do an unlimited 3G and 4G, I will stack them face to face, tack them on the four corners, put a tack in the middle between the two plates at both ends and then saw 1" off of the end, advance the plates in the vise and saw a 3/8" plus slice off for the coupons, then I will flip it over and repeat the same procedure on the other end of the plates. Once I have the coupons cut, I will remove the small portion of backing strip that is left and sand them in preparation for bending. Prior to sawing I will stamp a row of v's across the end of the vertical plate so that I can readily identify the vertical coupons from the overhead. Regards, Allan

By jwright650 (*****)

Date 04-30-2007 02:33

Yes Allen that is it...great little saw. I would love to have one like it at home in the shop.

By aevald

Date 04-30-2007 06:08

Hello John, I worked for a fab shop in Portland, Ore. in the early 80's, they had two of those saws. I loved the versatility and simplicity of them. Besides cutting 45's either direction and having vises on both sides of the blade, you could run them out to the end of their stroke and let them run against the stop and use them like a vertical bandsaw. I too wish I had one at my shop at home. Regards, Allan

By thcqci

Date 05-01-2007 20:59

Same saw I use here also and, yes, I would also love to have one in my personal shop!

By G.S.Crisi (****)

Date 04-25-2007 21:30

Do you know what a "power saw" is? I've always used that machine to cut coupons. It's slow, I agree, but it's also cheap, as your boss likes. If you don't have a great quantity of coupons to cut, a power saw is OK.
Now, ASME IX allows coupons to be cut with the torch ("flame cut" the Code reads)
Giovanni S. Crisi
Sao Paulo - Brazil

By aevald

Date 04-25-2007 21:49

Hello Giovanni, are you possibly referring to a friction saw or an abrasive cut-off saw? As I believe you have said in past posts,sometimes our differences in geographical area can affect our interpretation of terms. Regards, Allan

By G.S.Crisi (****)

Date 04-25-2007 22:43

Allan,
back in my days of erector engineer, I'd been in charge of the erection of a small thermal power plant (30.000 kW). The turbine generators were supplied by the firm C.A. Parsons, of Newcastle, England. Before the job started, Parsons' engineer handed us a list of erection equipment and tools that were necessary for the job. Among them, there was a "power saw", which consisted basically of a hack saw driven by an electric motor. A small reservoir supplied cooling water for the sawing operation. So, the term "power saw" is of English origin.
Yes, I know that English technical English and American technical English not always coincide, and this is an example.

A couple of other examples:
English: spanner American: wrench
English: Stillson wrench American: pipe wrench
English: clock gauge (with "u") American: dial gage
etc. etc.

Giovanni S. Crisi

By Lawrence (*****)

Date 04-25-2007 23:03 Edited 04-25-2007 23:05

I think this is one, We called them a "power hacksaw"

By aevald

Date 04-25-2007 23:07

Hello Giovanni, and thank you for the clarification and education. I do enjoy the wealth of information and facts that yourself and others bring to the forum. Once again I get to be educated a bit further. Regards, Allan

By G.S.Crisi (****)

Date 04-25-2007 23:58

Yes, Lawrence, it's exactly that.

Other examples:

English: turbo alternator American: turbine generator
English: bend (a pipe fitting) American: elbow (the same fitting)
English: sluice valve American: gate valve

Allan,
Among the "others" you also are included.

Giovanni S. Crisi

By bozaktwo1 (***)

Date 04-28-2007 23:48

Wouldn't a flame-cut on a sample change some of its properties?

By aevald

Date 04-29-2007 02:59

Hello bozaktwo1, to answer your question, yes. They typically specify to cut the specimens overwidth and then grind to allow for the removal of the heat affected surface. As to how much wider I don't recall. Regards, aevald

By 803056

Date 04-29-2007 18:02

Without looking it up, I believe I recollect 1/8 inch is to be removed from each torch cut surface to remove the heat affected zones.

Best regards - Al

By G.S.Crisi (****)

Date 05-01-2007 18:10

Problem is that grinding will also affect the properties of the ground surface.
Giovanni S. Crisi

By aevald

Date 05-01-2007 22:22

Hello Giovanni, when I prepare coupons I saw them out and then use a belt sander to complete the coupon preparation. I make sure that I have all of the sanding lines running the long way on the coupons and I also take care not to overheat them or change the color in the steel by over-sanding, I also sand a 1/16 radius on all of the corners of the long sides of the coupon. When I have completed the preparation the coupons have a nice tight, even, straight grain running the length of all four sides of them. I use 60 grit belts. Regards, Allan

By G.S.Crisi (****)

Date 05-02-2007 22:08

That's what I'd call a perfect preparation !
Giovanni S. Crisi