Spindle speeds for horizontal mill - cutting wheel

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

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Glenn Brooks
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Spindle speeds for horizontal mill - cutting wheel

Post by Glenn Brooks » Tue Sep 05, 2017 4:24 pm

Iam getting ready to make a bunch of 5" long mounting brackets, using 3" x3" angle iron. Thinking about using my Burke #4 horizontal mill with a 3" circular saw blade to cut the angle iron into individual brackets. (Probably need to made two cuts for each edge, due to height of the angle iron)

I assume the usual formula for diameter based vertical milling speeds -based on diameter of the saw blade- would be appropriate for the Burke in horizontal mode???

My second question is: I have a very robust auto feed mechanism on the machine. What physical characteristics of cutting with a wheel being pushed into the work with to much feed should I look for? The Burke is kind of a slow RPM machine, but has a very powerful feed mechanism. Come to think of it, the auto feed rate is linked to each speed. Are there some secret horizontal milling rules I should be aware of??

Iam still learning how to optimize cutting with the machine. Don't want to ruin to many wheels figuring out how to set it up properly.

Thanks much,
Glenn
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spro
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Re: Spindle speeds for horizontal mill - cutting wheel

Post by spro » Tue Sep 05, 2017 5:36 pm

Hi. What size arbor are you using ? I'm assuming it is around 1" and supported. "Saw blade" well fine but it can't be too thin because of the one key and aggressive feed. That could be different, just thinking about it. Mine came with a swivel vise and the jaws are 1" tall. If you get too much "ringing", you want to bolt it directly or lose the swivel base. If you have the original gear motor the feeds are pretty much right but structural steel isn't the same as milling a solid block in the vise. I know you already know this but here goes. My way would've been to clamp the angle upside down and cut the 90* to depth but I got out of that. That is okay for a bandsaw but not for a mill with power feed. Each side must be treated as a single flat surface. If you cut the web out first, there is no support for the later cuts. I used a section of accurate wood in the vise and clamped it tight so that each face was sawn, milled to depth.

spro
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Re: Spindle speeds for horizontal mill - cutting wheel

Post by spro » Tue Sep 05, 2017 5:46 pm

Btw. Why not a bandsaw and the mill used to true the parts ? The Burke 4 doesn't have much "Y" travel anyway.

Glenn Brooks
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Re: Spindle speeds for horizontal mill - cutting wheel

Post by Glenn Brooks » Tue Sep 05, 2017 7:41 pm

Yes, the arbor is 1". Reason I was thinking about cutting with a slitting saw is I don't have a large bandsaw - only a small, mini bandsaw from LittleMachineshop.com. It's too small to cut 40 pieces of 3"x5" angle.

Actually I think I will use the oxyfuel torch and just whack off the parts, or maybe use my power hacksaw. The hacksaw works but is slow, slower, and slowest cutting this kind of stuff. Didn't want to use the touch, as I wanted clean edges. But after making a prototype this afternoon, have decided to go with the torch for expediency. This is railroad trestle building after all. Not precision machining. So a light grinding to get rid of slag and rough edges may have to suffice. Outside case, the powerhacksaw might work quickly enuf, if I use smaller 2.5" angle iron footprint and weld on a short 4" x4" vertical flat bar extension to stiffen the vertical support post.

Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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John Evans
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Re: Spindle speeds for horizontal mill - cutting wheel

Post by John Evans » Tue Sep 05, 2017 8:37 pm

Stack several pieces in the power hacksaw and you will be cutting several pieces at a time rather than just one.
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Glenn Brooks
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Re: Spindle speeds for horizontal mill - cutting wheel

Post by Glenn Brooks » Tue Sep 05, 2017 9:29 pm

Thanks John, I will try what you suggest. My oxy adjust screw in the cutting torch head just blew out so into the welding vendor for rebuild - with a week lost - unless plan B comes along. Looks like it just did!

Nothing critical about the lengths of these pieces. They are just angle brackets to anchor 3x5 uprights forming each bent to the mud sill on my trestle. 1/4" plus or minus won't hurt anything... plus Don't want to spend 200 bucks for strong ties.

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

pete
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Re: Spindle speeds for horizontal mill - cutting wheel

Post by pete » Wed Sep 06, 2017 4:54 pm

Fwiw, rpm / feed rates are a factor of the blade diameter and the number of teeth so the usual 100 ft per min for a HSS cutter in mild steel would give a maximum rpm of 127. From my reading HSS saw blade type cutters are recommended to be run at about 60-70 per min. in steel. So ballpark the rpm at 70-90 rpm. Feed you'd want at least 2-3 thou per tooth so your making chips and the teeth aren't rubbing at any time. Count the teeth, multiply that by the rpm and multiply that by let's say .002" for your tooth load. That's your required feed rate per minute. Going too fast on the feed seems to rip teeth off on these fragile saw blades, but you still want a definite chip being formed. Structual steel angle iron isn't the best for machining so I think I'd want to be a bit conservative but looks like you may not be machining the ends anyway.

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