Machining a 1” Plate Welding Coupon

[erikmannie]

I know I sound like a broken record always talking about welding coupons. Here I am uploading in real time what I am doing.

Since I will be doing this over & over again, maybe somebody can provide some constructive criticism.

This is my first step. I put the A36 plate in like this & took off .015”. This cutter is a carbide insert 2 inch face mill. One lubricated pass at 900 RPM at about 13 ipm, & then a dry spring pass at 1200 RPM at about 6 ipm.

I know it doesn’t need to be great because it is a welding coupon, but I’m also taking the opportunity to hone my machining skills & learn to get a good surface finish.




I will do the opposite opposite side the same way, & there is no need to show that.

 

[erikmannie]

Next is a lubed .015” off the side with a 3/4” 3-flute, solid carbide EM at 1000 RPM, 13 ipm. I follow this with a dry spring pass at 1800 RPM, 6 ipm feed. I always use power feed.



The .015” pass did not completely remove the saw marks, so took off another .010”.

When I went to the other side, I just took off .025” from the get go.

I’m not happy with the surface finish:

 

[erikmannie]

Now I face .015” off of the top with the same carbide face mill. Lubricated 900 RPM, 13 ipm, no spring pass.

We note that I did not have to take the work in & out of the vice for this following the side milling operation above.




I am happy with the surface finish.

 

[aliva]

Curious, what welding test requires a 1" coupon?

 

[mattthemuppet2]

the finish on the side milling op maybe because of the material (generic mild steel) or the conventional (I'm assuming) cut. Try climb milling 10 thou off as a finish pass and see what you get.

 

[erikmannie]

Curious, what welding test requires a 1" coupon?

I do not know, although I had *assumed* a 1” (in this case) 1G SMAW test.

I am also assuming that it is helpful to practice different processes & positions on thick beveled plate.

Edit:

There is this test:

The AWS D1.1 1G Welder Qualification Test

The AWS D1.1 Structural Welding Code (Steel) welder qualification plate tests consists of a groove weld with a 45-degree included angle. The plates are prepared to a knife’s edge and a ¼ in [6 mm] backing strip is used. The test for unlimited thickness will use plates that are 1 in [25 mm]...

weldinganswers.com

Video example:

 

[erikmannie]

I got sidetracked because I had to install our gas dryer because *Lowe’s freakin’ sucks*!

Back to the project, I *had been* using this 80° solid carbide single angle cutter. It works really well, & using it yields a 40° bevel.



The problem with the above cutting tool is that it isn’t tall enough for a bevel on 1” plate. I need to compensate for this by machining 2 bevels, one on top of the other, & match them up. It is almost impossible to match them up perfectly… and then you’re taking down the last thou or so (where the 2 bevels don’t perfectly match) with an orbital sander. Not a long-term plan.

 

[mattthemuppet2]

that's a "tilt the head of your mill" job.

 

[erikmannie]

I bought this 1-1/4” thick, 6” diameter HSS single angle cutter which mounts to an R8 integral shank. I had to buy a 1-1/2” open end wrench to tighten the nut because my largest crescent wrench doesn’t open up to 1-1/2”.

I used some copper sheet, a tube block & a bench vise to tighten the nut on the stub arbor.

 

[erikmannie]

that's a "tilt the head of your mill" job.

That would be really easy. I could use a face mill.

I could machine a bunch of these in a batch, and then trammel the head afterwards.