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The old mill/drill vs small knee mill dilemma!

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  • #31
    Some great points I think tom_d
    I was hooding the belt changes would become easier over time and it sounds like an non issue to me. Like you say, adding vfd and 3 phase is always an option later on. I think having a more solid machine from the get go is more important for me.
    My smaller mill drill will still come in handy, for smaller work, plus it’s got to be very handy to have two machines setup hasn’t it.
    Im not to fussed about some of the RF’s extras over the knee mill. 95percent of my work is relatively small scale and I only do low numbers when it comes to production runs of parts. (Like 10 in a row).
    I have my own little machine shop business which is growing slowly within a fairly specific market- mostly bicycle related parts and my own tools which I design and sell online. Having the extra sturdiness of the knee mill makes sense to me, making the machine more futureproof. Plus I never know what sort of projects I may get.

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    • #32
      Pfowler, first off welcome to the madness...

      Work wise I think you'd be happy with either. As a retirement/new shop gift to myself was to buy one of the last of those knee mills that had the 6.5 x 29" table. The newer CX603 you're looking at was already on the floor beside the older CT504 that I got on sale for a LOT less money. I've been 110% happy with my new knee mill.

      From top down the two mills take up the same amount of room. The 45 is shorter of course but you make up for that by providing your own bench or using the box base as shown in the Bell pictures. But access room for the table travel is about the same for both.

      There would be no reason you could not use the vertical dovetail travel for Z axis cuts. Just need to keep the gib tuned correctly as with any movable dovetail.

      The belt drive head might seem a little fumbling at first but it has the same three cone pulleys with two belts setup as my drill press. And I long ago got pretty quick at switching belts around. The key to making this painless seems to be having enough motor travel to get enough slack and a good way to put back the tension while tightening the lock. And I for one prefer the quieter operation of a belt driven head even if it's only a little more noisy for a good gear head machine. And then there's always the risk that the gears on a particular machine won't be all that quiet.

      Mention was made of the work height for the knee vs column style. I rather like the fact that the cutter height where all the action is takes place at roughly the same height for all setups. With the dovetail column mill/drill style if you set up the machine so the smaller jobs just done in a vise or clamped directly to the table so that you don't need to bend over a lot then once you set up a tall arrangement with something like a large angle plate to allow working the end of a longer part or a rotary table in vertical mode suddenly the cutter is way up high. On my knee mill the cutter stays at the same height and the work settles lower. One way around this might be to set an RF45 a touch low and use a stool while running it with low setups after the setup and moving around is done from standing. Then any more grandiose taller setups can be done from standing.

      If you can pick up that whole shop all in one go I think you'd be extremely happy. The equipment looks really well maintained and for around this part of the world that's a very fair price for that much stuff.

      I was a bit worried that the list of tools in that "whole shop" package might not fit in only 200 sq feet. But really in my own 550sq ft area the actual machine and bench area is a little under 200 sq ft. The rest is a metal rack with grinders on top, motorcycles and storage. So with just a bit of care with the setup putting all that into 200sq ft is very doable.
      Chilliwack BC, Canada

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      • #33
        You will find that in real life, you do not need to change the belt speeds very often. Flat out for small cutters and the same for much larger shell mills if you keep the cut rate down. It is easy to hear the motor starting to labour, and that is the time to lower the speed, or reduce the cut rate. Solid carbide cutters up to 5/8", 16mm can be run at max speed, and it is well worth while getting some of the 50mm 4 insert shell mills which take APMT/ APHT 16 inserts which have two ends and can be bought cheaply in grades for steel and aluminium. Speeds should be lower if you use HSS cutters and lubrication is needed on steel as well as aluminium. Hopefully, the mill will have an R8 or BT30 spindle fitting.
        I have just looked at the advert and notice that the mill has an R8 spindle and is made in Taiwan.
        Last edited by old mart; 04-23-2020, 12:53 PM.

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        • #34
          Maybe I am missing something but all of the OP's pics seem to be dovetail column units, no round column. Anyway, getting to the question fo the round column vs the dovetail column, I have had a round column mill drill for over 20 years and I would never make that mistake again. The only pro that I have ever heard offered for the round column mill is that it offers a wider work envelope with it's ability to swing from side to side. I do not see this as a big advantage given the multiple cutters that have snapped off when the column has twisted to the side during a milling operation. Also, as previously stated, the inability to maintain position when the head is raised or lowered. Given the choice between a round column mill and nothing, I would probably buy a milling attachment for my lathe and live with those limitations.
          Fred Townroe

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          • #35
            One of us in an earlier post thought the RF-45 was the number for the older style round column mill drill. But that was generically known as the RF-30.

            I got sucked in by that as well about a year ago. The 45 style as sold under a lot of other distributor numbers is one of the heavier, if not the heaviest, dovetail column bench top mill/drills out there.
            Chilliwack BC, Canada

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            • #36
              if you have the tooling to swap over, that'll increase your overall budget some, that's for sure. The 8x30 comes stock with a taller column than the 6x26 that I have, so I think Z is around 16" compared with the 12" on mine. I'll be adding a 4" riser block at some time in the near future, so that'll solve that problem. I put a nice treadmill motor on mine and run a single belt, so have 4 speed ranges which cover me from 10rpm or so to over 3000rpm. That covers anything I'm likely to do, though a higher speed wouldn't hurt for really small end mills. I change the belt probably once every 3 months or so. I do desperately want a DRO, but I'm coping with the dials until I have the funds.

              To be honest, if used isn't an option (and Whistler BC never had a whole lot of industry) then your best bet is to go and try both and see which one you like the most. Capability and quality will be similar. Space occupied, likewise (mine's at the end of my half of a small 2 car garage). There's enough room to more or less walk between the end of the car and the mill. I remove the Z axis handle otherwise I occasionally get it in the nuts if I'm not careful.

              Click image for larger version

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              what kind of bike stuff do you make? For the Whister crowd?

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              • #37
                Originally posted by BCRider View Post
                One of us in an earlier post thought the RF-45 was the number for the older style round column mill drill. But that was generically known as the RF-30.

                I got sucked in by that as well about a year ago. The 45 style as sold under a lot of other distributor numbers is one of the heavier, if not the heaviest, dovetail column bench top mill/drills out there.
                This is true. An RF45 is dovetail machine weighing around 800+ pounds and doesn’t give up much to the 8x30 BP clones and I wouldn’t even consider a 6x26 version or Clausing 8520 instead of one. At the same price with a DRO, power feed, and power head I’d be going RF45. That BP clone isn’t as flexible as an actual BP, no ram movement. It likely isn’t as rigid as the RF45 either.
                Last edited by JCByrd24; 04-23-2020, 04:33 PM.

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                • #38
                  I'm still leaning towards the mill/drill with the DRO etc. Looks like an RF45 clone.
                  25 miles north of Buffalo NY, USA

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                  • #39
                    Matthemuppet, thanks for your input. It’s so good to talk to owners of these machines.
                    Here is some of my work...
                    My small mill drill has done me proud s far, and I always say it’s not the machine (to an extent) it’s the pilot who determines the quality of work. I do feel I’ve outgrown my machine now though.
                    First pic is of a custom mountain bike linkage I made for a local guy. Pretty intricate setups involved.
                    Attached Files

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                    • #40
                      Nice looking parts Pfowler67. All that done on a manual?

                      I'm pretty much in the same boat your in...been stuck on a 3 in 1 since '97. Killing me.
                      Been stuck deciding on a 2/3 B'port style or an RF clone. Hard to ignore the claims that say the RF has more rigidity.

                      G/L in your search.

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                      • #41
                        wow, fabulous work, especially the linkage (more travel? change in spring curve?) and the dookickeys in the last pic. Are they some kind of guided nut driver?

                        I don't have any experience on an RF45, so can't compare the two. Might be worth thinking about the future though - if your business expands, a CNC mill will massively increase your capacity and capability, and an RF45 has alot of support/ examples of people converting to CNC.

                        Weight-wise my 6x26 with stand is ~1000lb and I'd imagine an 8x30 would be a bit more.

                        One thing to play close attention to is the maximum height under the spindle and the overal work envelope (X/Y/Z travels). You can kind of work around X/Y travel limitations, but it's really easy to run out of Z. It's happened a bunch of times to me and it's a royal PITA. That's before considering rotary tables, dividing heads and the like.

                        A standard RF45 is 20x9.5x17.5, that Craftex 8x30 is 14.5x6x12.375 (XYZ). I don't know if those are the specs for the 2 mills you're looking at, but those are pretty big differences all round.

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                        • #42
                          The linkage was for the use of a certain shock which has an air chamber too large to fit inside the original link. It meant boring out that large space in the widest end of the link to make space for the shock. See pic.

                          As for the travels on the 8x30 machine, I noticed that other similar machines had more travel, so emailed Busy Bee to check the specs. Turns out they'd made a mistake (they've copied the spec from their smaller machine) and it actually has 17-5/16x8x21.5 (XYZ). So I think that will be good for me.

                          The guy selling his entire shop for 15k says he'll let me know if he ends up selling the machines separately, so fingers crossed.

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                          • #43
                            Oops, here’s that pic!
                            Attached Files

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                            • #44
                              Getting back on topic, does anyone have any input when it comes to mounting DRO to the knee mill? Particularly to quill travel? I have fitted DRO to my current mill/drill on X and Y, but haven't seen any examples of quill mounted DRO on the 8x30 knee mills, so thought i'd ask.

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                              • #45
                                I personally think I would prefer an RF-45 dovetail machine over a bridgeport, if I had to choose. It seems a compact and decent machine, but I got lucky and found a euro mill. Doesn't take a lot of space and is stouter and more rigid than a full size BP despite being smaller.

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