Should I be using Shell/Face mills or End mills on a Bridgeport J head?
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    Default Should I be using Shell/Face mills or End mills on a Bridgeport J head?

    I have a older BridgePort J Head with R8 collets I bought several years ago and I normally use it to mill 6061 Aluminum with no issues. I also inherited a bunch of shell/face mills Of all different sizes ranging from 2" up to 8".
    I have been working on a part that is 1018 Steel and have been cutting or shaping it with a 3/4" 4 flute HSS coated End mill.
    RPM = 1110
    Feed Rate = Max power Table feed
    DOC = 5mm
    WOC = 5mm per pass
    With Cool Mist spray
    Chips are coming off with a Bronze color to them.

    The Max material I need to Remove is 1" DOC x 1" WOC with a Total length of the part being 5". I'm not encountering any problems currently but I'm wondering if it would be more beneficial to use one of the shell mills instead. I'm thinking maybe the Shell mill will allow a deeper or wider cut or maybe it would just be better for wear instead of the End mill. It seems I could take a deeper cut with the End Mill but not Climb milling as the table will jump with backlash. I cant go any faster on the feed rate as it is maxed out (unless I turn it by hand).

    Anyway I would like to find a use for the Shell mills and not cause unnecessary wear on my end mills if possible. Any ideas?
    p1167286.jpg
    p1167289.jpg

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    For the most part those shell mills put too much load on an old Bridgeport. I have a Taiwanese
    clone that weighs probably 1000 lbs. more and I wouldn't bother with shell mills. If you want to
    remove material "fast"--a relative term-- I'd buy some roughing end mills. They will gobble up the
    material.

    Take your 1" x 1" slot as an example. One 15/16" deep pass down the centre with a 7/8" rougher
    leaves you 1/16" to clean up on 3 sides--much faster than anything else you can try...

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    I've never used a roughing mill. Do be clear are you saying I could make a 15/16" x 7/8" slot in One pass with a roughing mill? If so then that's definitely the way to go!

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    Quote Originally Posted by leef28 View Post
    Anyway I would like to find a use for the Shell mills and not cause unnecessary wear on my end mills if possible. Any ideas?
    So, you'd rather wear out a several hundred $ shell mill than a cheap end mill? Don't make sense to me.

    If you want a insert mill, that's a little different story. Stay BELOW 3". Do you want square shoulder cutting? Expect to shell out some big bucks. We're talking $500-800 for the insert face mill, $100 for the arbor, and up to $20 each per insert.

    Above all else, lay off the flycutters. The hobbiest friend. They just beat the crap out of the spindle and bearings on a BP.
    JR

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    Quote Originally Posted by leef28 View Post
    I've never used a roughing mill. Do be clear are you saying I could make a 15/16" x 7/8" slot in One pass with a roughing mill? If so then that's definitely the way to go!
    Basically, yes. Start out at around 300 RPM and push the feed. The machine will tell you when it;s happy. Use
    flood coolant or at least a mist type coolant spray--keep the cut clear. You don't have to have 7/8" end mill. You
    can use a smaller cutter and make a second pass to leave about .030" for cleanup. Experiment to find out what
    works best for you...

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    Quote Originally Posted by leef28 View Post
    Anyway I would like to find a use for the Shell mills and not cause unnecessary wear on my end mills if possible. Any ideas?
    p1167286.jpg
    p1167289.jpg
    HSS endmills are popcorn. Meant to be eaten-up. No shortage of cheap ones as can deal with shiney-wood and other plastics. Many of the Carbides are even cheap nowadays. CAVEAT: They may be "cheap" because that aren't very GOOD, too. Premium-performing cutters can, and DO earn premium prices. Also still make money for those who need that extra edge and can put it to good use.

    The cutters in the photos look to be HSS, possibly an exception or so, so you can't GET much for them.

    Might save them in case you someday acquire a small/medium Horizontal mill and develop a taste for milling STEEL and the Bronzes with its slow "crunch, crunch, crunch .." and the stench of dark brown sulphurized cutting oil.

    And "Oh, BTW" department? A flycutter isn't limited to molesting a BP. Hard on any spindle.

    Also potential bad news from a safety aspect as well. THERE's another use for an insertable shell or face mill.

    Leave it loaded, full-house. Do the do. Then shim one good, clean insert proud just a skosh for a final mirror-bright clean-up pass as if it were a flycutter.

    Waaaay safer than a flycutter if you screw the pooch and try for a crash, 'coz the OTHER inserts will still take a bite before you get so deeply in as to play motor-driven pry-bar 'tween work and spindle.

    2CW

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    Quote Originally Posted by leef28 View Post
    I have a older BridgePort J Head with R8 collets I bought several years ago and I normally use it to mill 6061 Aluminum with no issues. I also inherited a bunch of shell/face mills Of all different sizes ranging from 2" up to 8".
    I have been working on a part that is 1018 Steel and have been cutting or shaping it with a 3/4" 4 flute HSS coated End mill.
    RPM = 1110
    Feed Rate = Max power Table feed
    DOC = 5mm
    WOC = 5mm per pass
    With Cool Mist spray
    Chips are coming off with a Bronze color to them.

    The Max material I need to Remove is 1" DOC x 1" WOC with a Total length of the part being 5". I'm not encountering any problems currently but I'm wondering if it would be more beneficial to use one of the shell mills instead. I'm thinking maybe the Shell mill will allow a deeper or wider cut or maybe it would just be better for wear instead of the End mill. It seems I could take a deeper cut with the End Mill but not Climb milling as the table will jump with backlash. I cant go any faster on the feed rate as it is maxed out (unless I turn it by hand).

    Anyway I would like to find a use for the Shell mills and not cause unnecessary wear on my end mills if possible. Any ideas?
    p1167286.jpg
    p1167289.jpg
    .
    corncob roughing endmill has less vibration from the wack wack wack of milling. thus can usually remove more material per minute at same vibration and hp levels.
    they leave lines from side milling cause sharpened like a corn cob
    .
    crest cut end mills can do roughing and finishing thus are still popular
    .
    carbide insert mills are popular finishing wide surfaces faces in fewer passes

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    Thanks for the advice, all of you!

    I found a 3/4" cobalt roughing end mill. Set the rpm to 300 and hand fed with cool mist. The cutter caused a lot of vibration even at half the recommended DOC and WOC. But it seemed to cut well without stressing the motor. So I tried the automatic feed at the same rate as by hand made a few passes and while re positioning the cool mist nozzle mid pass the end mill snapped in half. I directed the mist away from the cutter for a split second and then back on it and it snapped right when the spray hit it.
    Not sure, but I'm assuming the hot/cold shock caused the break. As DOC rpm etc. Was all the same.
    Anyway material removal rate was much better. While machine vibration much worse.

    I actually recently bought a lagun 5hp cnc mill that I'm sure would be better suited to mill out these parts. Unfortunately the part I'm making is the ball screw bracket for the Lagun mill which is currently broken.
    Cheers!

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    Quote Originally Posted by leef28 View Post
    Thanks for the advice, all of you!

    I found a 3/4" cobalt roughing end mill. Set the rpm to 300 and hand fed with cool mist. The cutter caused a lot of vibration even at half the recommended DOC and WOC. But it seemed to cut well without stressing the motor. So I tried the automatic feed at the same rate as by hand made a few passes and while re positioning the cool mist nozzle mid pass the end mill snapped in half. I directed the mist away from the cutter for a split second and then back on it and it snapped right when the spray hit it.
    Not sure, but I'm assuming the hot/cold shock caused the break. As DOC rpm etc. Was all the same.
    Anyway material removal rate was much better. While machine vibration much worse.

    I actually recently bought a lagun 5hp cnc mill that I'm sure would be better suited to mill out these parts. Unfortunately the part I'm making is the ball screw bracket for the Lagun mill which is currently broken.
    Cheers!
    roughing cutter at same metal removal rate has less vibration. more likely your machine is vibrating cause it cant handle the increased cutting forces. many end mills when no coolant, chips will stick to flutes and cause stuck material in the way cutting forces will increase 100 to 1000%. also length cutter sticking out of tool holder is the most important limiting factor. at 1.5" stickout for a 3/4 dia end mill you can remove a lot as long as chips can get out of the way fast enough. BUT if you double from 1.5 to 3" stickout the same 3/4 end mill will vibrate 2x2x2 or 8 times more and need to reduce cutting removal rate usually by less depth and width of cut basically remove 1/8 as much per minute
    .
    i have used thousands of roughing end mills close to 40 years. they work better at roughing thus why they are designed to be better at it. but you need to be aware they require more hp. a 2" dia roughing end mill often will need 5 to 10hp. many a light weight machine cannot handle it without excess vibration and chatter
    .
    a 3/4 dia roughing end mill can easily exceed what a light weight 1.5hp mill can handle. same cutter on a 20hp machine and it will not only handle it it can usually take a lot more
    .
    if you are full width slotting with a roughing end mill its very important to get the chips out of the way fast enough. usually flood coolant or compressed air is needed to blast the chips out of the slot

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    Quote Originally Posted by leef28 View Post
    I have a older BridgePort J Head with R8 collets I bought several years ago and I normally use it to mill 6061 Aluminum with no issues. I also inherited a bunch of shell/face mills Of all different sizes ranging from 2" up to 8".
    I have been working on a part that is 1018 Steel and have been cutting or shaping it with a 3/4" 4 flute HSS coated End mill.
    Use a roughing 3/4" end mill for cutting and shaping. Save you 4 flute for the finish work.

  11. #11
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    Did you try the cutter at a lower RPM? My mill is probably more rigid than yours--but not by a whole bunch---and I
    can always find a sweet spot where it will walk a roughing mill through a chunk of material with no vibration. Start
    slow and work your way up...


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