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Thread: Machining Steel and Aluminum on a Mill/Drill

  1. #1
    Join Date
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    Default Machining Steel and Aluminum on a Mill/Drill

    Hey Guys

    I am new to the forum. I am considering purchasing a mill/drill for my shop at the farm. It would be used primarily for making or modifying small parts to repair farm equipment.

    I am looking at a gear head unit with six speeds ... 115, 220, 320, 600, 1120, 1700. Are these speeds sufficient to machine both steel and aluminum? There is a variable speed unit that runs at 40-3000, but it costs an additional $400.

    What are your thoughts. Thanks.

    Mike

  2. #2
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    MW, Welcome Aboard ! ! !

    For basic mods and repairs it'll be lovely if it's a reasonable size to take the sort of pieces you want to work on. The bigger the table the better. But also the more room from table to spindle the better. It's surprising how if you start doing things with rotary tables and other work holding options then a basic vise how the added parts chew up vertical room. So don't go too small. If you're looking at a table top mill/drill the version with rather square'ish cast box column is the best bang for the buck in its class. It's generically called the RF45 by the folks around here. Grizzly sells this particular model as their Model G0761. The defining measurement and feature is the large column all cast in iron and the 9.5 x 31.5 inch size table. You get that and you get the best in the class for bench top mill/drill. And truly this machine does not give up much, if anything, to the smaller knee mills in many ways.

    Variable is nice. But if you're only doing jobs on the mill here and there, like maybe once a week for a hour or so, then the fixed speeds listed will be just fine. There's a couple of small mods you can do that make switching speeds faster and more convenient which fills in a small but significant advantage gap of having a variable speed feature. And if you're not going to be a regular machining guy then that $400 could be put to good use for accessories for the mill/drill.... like a good milling vise or rotary table.

  3. #3
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    Thanks for your thoughts ... I am new at this type work. You answered my question. BTW, I plan to get a square column machine.

  4. #4
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    The G0761 looks like a very capable machine, but it is $2400, and you might find a used Bridgeport for about the same price, possibly with a good complement of tooling. I have a Harbor Freight round column mill that I bought about 15 years ago for (IIRC) about $600, and it has served me well, within its limitations. It is somewhat similar to the Grizzly G0760 ($2000) or maybe G0705 ($1650). The Harbor Freight latest version is similar, and about $1200. It is a 12 speed belt drive, which is a bit inconvenient, but probably better than a variable speed, which may not have adequate torque at the low end. You can always get a VFD for about $200 and a 3 phase motor for about the same price.

    One advantage of the smaller mills, like mine, is that it is possible for one person to partially disassemble and move. I did the same for my 9x20 lathe.

    I was able to mill the rear axle support for my Craftsman riding mower / tractor with my mill, even using the drill chuck as an end mill holder:








    Welcome to the forum.

  5. #5
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    I have been pondering of getting new drill-mill and try to find some youtube videos showing what these are capable without much luck.
    Too many videos where everything is done half-arsed or someone just grinding the workpiece with endmill.

    What is the maximum cut you can expect to take with endmill on RF-45 size machine? Or round column G0705?

  6. #6
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    I haven't really pushed my milling machine to the limits, but here are some videos that show it working:

    http://enginuitysystems.com/files/CA...lling_1809.AVI (78 MB, 1/2" aluminum)

    http://enginuitysystems.com/files/CA...oject_1544.AVI (81 MB steel)

    http://enginuitysystems.com/files/CA...oject_1569.AVI (150 MB 0.010 DOC steel)

    http://enginuitysystems.com/files/CA...oject_1580.AVI (70 MB steel)

    http://enginuitysystems.com/pix/tools/T-nuts_1535.AVI (75 MB steel)

    http://enginuitysystems.com/pix/tool...minum_2723.AVI (112 MB .030 DOC 1/4" aluminum)

    http://enginuitysystems.com/pix/tool...minum_2725.AVI (91 MB 1/2" HF 2-flute EM 1/4" aluminum)

    http://enginuitysystems.com/pix/tool..._4140_1493.AVI (96 MB 1/4" slot in 4140)

    Some of those videos were taken before I became more comfortable with using higher speeds, deeper cuts, and faster feeds. I also now have some better tooling.
    Last edited by PStechPaul; 12-07-2018 at 04:58 AM. Reason: link error

  7. #7
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    I have an old 3-phase RF-31, with the wide range of speeds. I do use the really low speeds on occasion, for things like fly cutters and slitting saws. I also occasionally use the high speeds for drilling small holes in aluminum, but the slower speeds will work for that. If you don't anticipate doing much of those things, the regular range will work fine.

    allan

  8. #8
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    Your on the right track with that gearhead mill,a freind has one that get used lots.Where do you farm at?

  9. #9
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    The speeds will do fine, you just go a little slower and save $400. Use a little WD40 or similar when milling aluminium. Get a few cheap solid carbide end mills from 1/4" to 1/2" and possibly a shell mill of about 2" which takes APHT/APMT tips. There are plenty of cheap Chinese ones on ebay and the tips for steel or aluminium only cost about $10 a box of ten.

  10. #10
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    Quote Originally Posted by MattiJ View Post
    I have been pondering of getting new drill-mill and try to find some youtube videos showing what these are capable without much luck.
    Too many videos where everything is done half-arsed or someone just grinding the workpiece with endmill.

    What is the maximum cut you can expect to take with endmill on RF-45 size machine? Or round column G0705?
    The round column machine I had some chances to use was able to hog away a 6mm x 12mm pass in steel at around 3 to 4cm/minute. But it was pretty much at it's limit with that sort of pass. The finish of the cut was rather rough. And it really does not take much to mess that up and reduce the dimensions of the pass to something more modest. To do a pass of that size I found that the cutter needed to be in really good condition and the setup of holder and extension needed to be short as possible in all ways.

    i'd expect the square column to be better for not flexing than the smaller round column. It's a larger size than the round column and uses the same or more metal. So it should be stiffer.

    What I found with the mills I've run is that more often than the machine itself being a limiting factor the end mill setup is the issue. An end mill that is losing the sharpness needs more pressure to force the cut. And that makes the end mill flex more and shudder (chatter) in the cut. And if the end mill holder is one of the longer style holders and if the end mill itself is not choked up in the holder or collet to reduce the overhang from the last bearing by as much as practical then this seems to lead to more movement of the actual cutting edges and a poor result.

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