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Thread: Machining Steel and Aluminum on a Mill/Drill

  1. #11
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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?
    Hi,

    There are a few variables to be considered beyond rigidity of setup for benchtop mills.. Head height matters a lot. The lower to the table is better. Variable speed vs gear head. My VS G0704 can run as slow as 50rpms, but is pretty near useless below 300rpms. If the little Chinese pony sized 1hp motor ever dies, I will replace it with a VFD setup. And finally cutter type. Roughers vs plain, ball vs square. And even material type matters - HSS vs carbide.

    My smaller BL-20/G0704 style mill, which is smaller than the RF-45, can do .100"/2.54mm depth of cut in mild steel with a 3/4"/20mm HSS endmill@2"/50mm per minute or so. I could increase the feed rate by going to solid carbide or even a just a HSS rougher. I don't push it that hard regularly, but it can do it. So a RF45 is at least that good.
    If you think you understand what is going on, you haven't been paying attention.

  2. #12
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    North Alabama
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    Thanks to all for your comments ... especially to Paul for the photos. That is exactly the type of repair work in envision doing with the mill. BTW, I am leaning toward the Precsion Matthews 727M. I realize that the Grizzly mentioned is a more substantial, but it is larger and more expensive than my budget.

  3. #13
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    I would reconsider that PM. Haven't heard good things...

    Money well spent and probably around the same price point with a little patience will get you:

    https://www.youtube.com/watch?v=9Tmf...ature=youtu.be

    https://www.youtube.com/watch?v=fpp4...ature=youtu.be

    Chips and quarters


  4. #14
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    That 727M has a far smaller front to back column. Which would be fine for use with smaller size cutting tools and lighter cuts. You could peck your way through a larger piece and remove the metal in due time. But it'll take you more passes. Possibly quite a few more. If time is money when you're working at the mill you may well find that it's better to pay more up front so that any jobs you do on the mill to service your equipment will see the machine back up and operating again sooner instead of later. If this was strictly for a hobby then that would be different and you could tolerate slower.

    OR, you could buy and start using this machine now and as a future project fabricate a stiffening and damping structure to attach to the rear of the column.

  5. #15
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    Jun 2016
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    Quote Originally Posted by MWCurl View Post
    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
    I'd say go with the variable speed because of the wider range of spindle speeds. 1700 RPM is pretty low -- you want more than that running a 1/4" end mill in aluminum.

  6. #16
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    Ok, my two cents worth;

    If doing repair work, you will not know in advance what size things will be. In that case get one with the biggest work envelope that you can. There are several things that determine the limits of the what you can work on. They include swing, table size, table movement, head movement up/down and head movement in and out, spindle extension, and knee travel and distance from spindle to table top.

    Swing is the diameter of the biggest disk that you can mount to the table with the center of the disk under the spindle. You can cut the whole disk by moving the table left/right + in/out and rotating the disk.

    Table movement is often much smaller than the table size. The table dovetails must remain in the bed/knee. A 30 inch table often only moves 25 inches or so.


    In a business the down time while repairing may cost you hundreds or thousands of dollars per hour. It's often worth while to buy more capable (and often more expensive) tools to get the job done faster. A knee mill with the head mounted on a ram (bridgeport style) will often give you the best capabilities for unanticipated large work.

    Having said that, I've seen great work done on all the popular mill styles when the work was within the envelope of the machine. That includes some fantastic custom work done cheap imports and 3-in-1 machines too.

    Dan
    Measure twice. Cut once. Weld. Repeat.
    ( Welding solves many problems.)

  7. #17
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    Quote Originally Posted by danlb View Post
    Ok, my two cents worth;

    If doing repair work, you will not know in advance what size things will be. In that case get one with the biggest work envelope that you can. There are several things that determine the limits of the what you can work on. They include swing, table size, table movement, head movement up/down and head movement in and out, spindle extension, and knee travel and distance from spindle to table top.

    Swing is the diameter of the biggest disk that you can mount to the table with the center of the disk under the spindle. You can cut the whole disk by moving the table left/right + in/out and rotating the disk.

    Table movement is often much smaller than the table size. The table dovetails must remain in the bed/knee. A 30 inch table often only moves 25 inches or so.


    In a business the down time while repairing may cost you hundreds or thousands of dollars per hour. It's often worth while to buy more capable (and often more expensive) tools to get the job done faster. A knee mill with the head mounted on a ram (bridgeport style) will often give you the best capabilities for unanticipated large work.

    Having said that, I've seen great work done on all the popular mill styles when the work was within the envelope of the machine. That includes some fantastic custom work done cheap imports and 3-in-1 machines too.

    Dan
    X2 what Dan said,don't know what type of repairs your doing on the farm.If mechanical handy take a look at some of heaver iron which sometimes is really cheap.I'm talking bigger than B port if you have room that is.I used a Mill Drill for 25 yrs and did a lot of work with it,Table size allways seemed to small.I got a larger knee style Mill for cheap and refurbished it and have no regrets,it was not a plug and play machine thou.

  8. #18
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    While I can understand the cost of down time in a big shop with lots of employees and making big expensive equipment I don't see that being the case here.

    First off he's running a farm. And yeah, if a machine breaks down at a busy and time crucial moment then Things Need To Get Done! But for some time until MWC comes up to speed and learns how to get a fix done in a hurry I don't see him using the tools to do such repairs. I see this as more of a winter down time "let's repair that stuff because we've got some time now" sort of deal. So one or two steps up the ladder from home hobby type making stuff with no real final application other than making smiles. And MANY rungs below a millwright's shop inside of some big production plant with 20 wage earners sitting with their fingers up their backsides because the line is down.

    Now having said that the folks around here with farms and BIG sheds seem to have a good amount of floor room for some big iron. But the issue becomes how does a newcomer to machining learn enough without doing any machine time to know what to look for in a used machine? I know there's lots of "look at the cherry machine I got for a song" stories. But I think it's fair to say that most old and well used/abused machines come with warts aplenty that need to be fixed before good work can be done.
    Last edited by BCRider; 12-08-2018 at 06:33 PM.

  9. #19
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    Quote Originally Posted by BCRider View Post
    While I can understand the cost of down time in a big shop with lots of employees and making big expensive equipment I don't see that being the case here.

    First off he's running a farm. And yeah, if a machine breaks down at a busy and time crucial moment then Things Need To Get Done! But for some time until MWC comes up to speed and learns how to get a fix done in a hurry I don't see him using the tools to do such repairs. I see this as more of a winter down time "let's repair that stuff because we've got some time now" sort of deal. So one or two steps up the ladder from home hobby type making stuff with no real final application other than making smiles. And MANY rungs below a millwright's shop inside of some big production plant with 20 wage earners sitting with their fingers up their backsides because the line is down.

    Now having said that the folks around here with farms and BIG sheds seem to have a good amount of floor room for some big iron. But the issue becomes how does a newcomer to machining learn enough without doing any machine time to know what to look for in a used machine? I know there's lots of "look at the cherry machine I got for a song" stories. But I think it's fair to say that most old and well used/abused machines come with warts aplenty that need to be fixed before good work can be done.
    I have to agree with some of your comments,but in Rural areas some acreages or farms have room for some of size of the machines I was referring to,your not putting them in a basement or house garage.As far as a newbie starting with a large machine or small one functions are pretty similar.It would be good to know where this fellow is located and when he said farm repair that is a wide spectrum,who knows maybe he's lives next to one the members on here.I am always game to go look at machines with anyone who has interest in them.Your right a lot of older machines may have issues but maybe this guy is a mechanical wizard.It even seems some of the lower cost new machines have issues being brand new.I have learned myself that a lot of older heavy machines never get a second look.I looked at a Russian made Drill Press when I built the new shop it was ugly but had insane quill travel 8-10" and belt drive to a reduction gear box with 3 ph motor.Was in the market for one and drove to KMS and bought the biggest General floor model they had, it was a nice drill press but was disappointed in flex when leaned on.I beleive some one posted about that a while back,the Russian was similar foot print bigger column and way heavier regret not buying it.I am no mechanic or engineer but some of the bigger stuff is worth a look sometimes .A lot of farmers have big loaders or telehandlers that can deal with these machines.
    Last edited by Tundra Twin Track; 12-09-2018 at 11:46 AM.

  10. #20
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    I think the key phrase in your question is "... making or modifying small parts to repair farm equipment." A small part for a farm tractor is not something that will fit inside a Swiss watch. You are talking medium sized parts and up. This is key because the size of the tooling is roughly proportional to the size of the part. So you will not be using 1/16" end mills very often. Probably more in the 1/4" to 2", 3" or even 4" diameter range most of the time. And the spindle speed is inversely proportional to the tool's diameter: small tools are run faster while larger ones need to go slower. This is to keep the linear cutting speed relatively constant.

    Like you, my shop is not a commercial one. Like you, I do odd jobs, mostly one or a few of a given part and then I am moving on to something else. So my overall speed in making them is not as important as the fact that I CAN make them. I have a gear head mill with six speeds from 50 to about 1500 RPM and I find that speed range is OK for most of the work that I do. If anything, the low end of the range is more important than the high end. My 50 RPM is often useful for large diameter tools. I can afford to take more time when using a smaller tool which may allow a speed faster than the 1500 RPM maximum that my mill allows. I seldom use the 1500 RPM setting.

    Many will talk about the fact that carbide tooling "likes" faster speeds. I am not experienced enough to completely confirm that. But I can tell you that the carbide tooling that I have works just fine with the limited speed range of my mill. That includes a 3" facing cutter with carbide cutters. I think that the real reason for running carbide tooling faster is because it can be run faster and by going faster, a machinist, in a COMMERCIAL shop where speed is money, can make more parts per hour. It is economics, not any real need for then carbide tool to go faster. OK, there is the "finish" thing. And that is an area where my experience is lacking. From what I have seen, HSS gives me a better finish. And carbide gives me an OK finish, even at my lower speeds.

    Another thing that you need to understand with that tool size and speed (RPM) thing is that a proper comparison of different tool speeds should be made with the same HP (horsepower) being delivered to the tool. Many variable speed machines use a VFD or Variable Frequency Drive to achieve a slow speed. A characteristic of many VFDs is that they deliver about the same torque at all speeds. This sounds good, but it isn't. Keep in mind that horsepower is equal to the Torque times the RPM divided by a constant (HP = T * RPM / K). So if the speed decreases while the torque remains the same, the HP is reduced. Therefore, if you are going to use a larger diameter tool then you need more torque, not the same amount. Torque is the product of force and the length of the lever arm that is applying it. So a larger diameter cutter has a larger lever arm (radius) and needs more torque to apply the SAME cutting force at the cutting edge.

    So slowing a larger cutter down with the constant torque of a VFD may help to prevent the tool from getting dull, but it will not allow it to take a deeper or faster cut. That goes for HSS or carbide tooling. The gearing of a gear head machine does keep the delivered HP relatively constant and you do get more torque at slower speeds. Gears are the ideal way to control the spindle speed of a machine, not a VFD. Of course, you can combine the two and use the gears for a rough speed setting while the VFD provides the fine adjustment. Unfortunately, that is not how most machines with VFDs are set up for use.
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

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