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BT30 Spindle Capabilities

DavidScott

Titanium
Joined
Jul 11, 2012
Location
Washington
Helical # 82012

Can you please share what parameters you use for a 3/8 end mill.
I looked up your end mill, it is a rougher/finisher, which work a lot more like a finisher than a corn cob rougher. Try a Garr corn cob rougher #46303, get 3 of them so you can break one seeing how fast you can feed it. I looked at their speeds/feeds chart and it is hopelessly conservative so ignore it. MA Ford has a much more realistic one for their same type tools. For side milling they show up to a .035" chip load with a 3/8" mill, yes that is per tooth, which is realistic. I can't give you specific parameters to use since they totally depend on what you are doing, and how well you can hold onto your part AND flush the chips out. You may not want to run full rpms so once you get the machine making parts play with the over rides to see what you think you can do. You may be better dropping your rpms so you make fewer but larger chips that are easier to flush. Don't get hung up thinking you know anything, just play with the feeds and speeds for a while, and don't be afraid of breaking an end mill, that is why you got extras. If you do this I can guarantee you will end up running that rougher far harder than you ever imagined. Play with width of cut too, I like around 40% with corn cobs when side milling. That would be around .15" with a 3/8" mill. That might be a little much at 1" doc but it might not too.
 

Chips Everywhere

Aluminum
Joined
Apr 29, 2021
I looked up your end mill, it is a rougher/finisher, which work a lot more like a finisher than a corn cob rougher. Try a Garr corn cob rougher #46303, get 3 of them so you can break one seeing how fast you can feed it. I looked at their speeds/feeds chart and it is hopelessly conservative so ignore it. MA Ford has a much more realistic one for their same type tools. For side milling they show up to a .035" chip load with a 3/8" mill, yes that is per tooth, which is realistic. I can't give you specific parameters to use since they totally depend on what you are doing, and how well you can hold onto your part AND flush the chips out. You may not want to run full rpms so once you get the machine making parts play with the over rides to see what you think you can do. You may be better dropping your rpms so you make fewer but larger chips that are easier to flush. Don't get hung up thinking you know anything, just play with the feeds and speeds for a while, and don't be afraid of breaking an end mill, that is why you got extras. If you do this I can guarantee you will end up running that rougher far harder than you ever imagined. Play with width of cut too, I like around 40% with corn cobs when side milling. That would be around .15" with a 3/8" mill. That might be a little much at 1" doc but it might not too.

My biggest concern right now is the BT30 pull stud, after seeing one for the first time a week or two ago, it really made question how fast I can rough on a BT30. That's why I started with 180imp. I'm not saying they are not capable of roughing, I'm just afraid of snapping the pull stud and not the end mill. I'll order some of those end mills and give them a try.
 

LOTT

Hot Rolled
Joined
Nov 28, 2016
My biggest concern right now is the BT30 pull stud, after seeing one for the first time a week or two ago, it really made question how fast I can rough on a BT30. That's why I started with 180imp. I'm not saying they are not capable of roughing, I'm just afraid of snapping the pull stud and not the end mill. I'll order some of those end mills and give them a try.
We snap off 3/8" roughers from time to time, usually from misloaded stock (never from my programming, of course....). The pull stud doesn't care, especially with the stubby holders (these are the Maritool high strength stud).

Seconding (thirding?) the knuckle/corncob roughers, they run free-er and the chips are more compact to boot. And I don't think the generate as much helical pull.
 

bosmos_j

Hot Rolled
Joined
Jun 9, 2015
I use the JM high strength pull studs on heavier cutting stuff. The Maritool ones are probably fine, I just like the JM ones better. They have a longer thread relief which puts the threads farther into the toolholder (this is patented by them come to find out). I was optimistic when Maritool decided to upgrade their stud... however, they left 0.5mm of diameter on the table (small dia is 7mm vs. JM at 7.5mm). Would be odd if the patent prevented them from doing that. Who knows. I use 38 degree helix rougher from Maritool. The 45 degree ones will generate more pull.

jm25084ahths (non-thru)
Edit: this pn is for a speedio.

 
Last edited:

DavidScott

Titanium
Joined
Jul 11, 2012
Location
Washington
My biggest concern right now is the BT30 pull stud, after seeing one for the first time a week or two ago, it really made question how fast I can rough on a BT30. That's why I started with 180imp. I'm not saying they are not capable of roughing, I'm just afraid of snapping the pull stud and not the end mill. I'll order some of those end mills and give them a try.
The problem with BT30 pullstuds is NOT the studs, it's the 500-600lbs of drawbar force on many machines. What generally breaks the studs is when the drawbar force is overcome pulling the holder partially out of the spindle. Since it is in the cut the holder is held to the side rolling around in the spindle so the pullstud is at an angle to the drawbar. This rolling side load is really hard on the pull stud. I think Maritool pull studs are through hardened and are a bit more sensitive to this side load. This is why you need to keep your projections to a minimum and be careful of using tools that pull too much like bigger end mills and high helix. A common problem I have with my parts is holding onto them so I am pretty sensitive to cutter pressure and lift. Corn cobs for roughing really reduce the cutter pressure and greatly reduce the lift so I can run them much faster without the parts moving.

How much drawbar force does your DT2 have? My Kitamura has 900lbs and it is much less sensitive to tool projection than any other 30 taper I have ever used. This extra drawbar force also gives you more insurance when problems happen.

Standard pull studs for a Brother are good to around 12,000 lbs tensile but they do spec a special that is slightly bigger than the standard spec, with bigger radiuses at the neck, they are just harder to find and more expensive. For my $$ I use TJ Davies studs and have never had an issue.
 

Chips Everywhere

Aluminum
Joined
Apr 29, 2021
I doubt its true.

I really wish I ended up with a Brother, the tapping on this machine is slow and the surface finish is not as good as the VF2SS with the same cutting tool and parameters. Small quality control problems just keep showing up daily.
 








 
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