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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > RF-45 Clone Mill > ENCO RF45 Clone CNC Conversion - LinuxCNC
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  1. #1
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    ENCO RF45 Clone CNC Conversion - LinuxCNC

    Hello all,

    I am currently working on converting an ENCO RF45 clone that I purchased in the fall of 2013. I am pretty much following in others footsteps but I am doing a few things differently so I though I would document my endeavors here in the hopes it might be of value to someone.

    First, a quick history. I purchased the mill when I was a freshman studying Mechanical Engineering Tech at Southern Poly. I used the mill for several projects during the spring of 14 but a defective spindle motor made it less than reliable so I mostly used the school’s equipment during that time.

    During the summer of 14, while waiting on replacement motors, I took the opportunity to completely tear down and rebuild the mill. I replaced all the bearings, added oil groves to the ways, repositioned some of the gears in the head to reduce noise, and stripped to iron, filled and repainted.

    Overall I was very impressed with the quality of the machine; the castings were crisp and sound, the fit and finish excellent. I think it is a step above the IH or Charter oak machines in term of quality, though it is a little smaller. ENCO’s customer service was excellent and we did eventually get the motor problem worked out. It turned out that I was one of the first few to purchase that particular mill model from ENCO, and while the motor was a good quality American made unit the capacitors were not sized correctly which caused the centrifugal switch contacts to fuse together. After sending me 5 motors with small caps they finally got the right size and it has run fine since.

    After the rebuild I used the mill extensively for school related projects and for making and repairing equipment for the school’s Nuclear Lab which I manage. Several of these project required some complex parts and made me think more seriously about converting the mill to CNC. Finally this past summer I made some time between grading assignments, running the lab and doing homework to begin working on the design for the CNC conversion. I completed most of the design work and was able to order the axis motors and ball screws before the fall semester started.

    I had to use the mill much of the Fall semester so could not make much headway on the conversion until recently, when I graduated. I now have a little more time to work on the conversion and to document it here.

    I have complete CAD model and drawings of the conversion that I will be posting soon for your criticism.

    I’ll get into the CNC part in the next post, but it is late so for now here are some "historical" pictures of the mill.


    Fresh off the Truck (My sister does not look to happy about my new toy!)


    Nice Castings and Shiny New Paint


    Current State

    Also, here is an album with a bunch of pictures during the rebuild. Hope you all like pictures!
    https://goo.gl/photos/zY3e6AjbmZQdVFW67

    More to come. Thanks for looking!

    Kurt

    P.S. This is my second time posting anything, anywhere. Hope it works.

  2. #2
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    ENCO CNC Conversion - The Design

    OK, so I don't know where to start. I guess I'll start with the design so you'll know where I'm heading.

    Our 1.5 car garage shop is used for many different purposes; from metal and woodworking, to use as a greenhouse for plants in the winter, to serving as a chemistry and nuclear physics lab. So I want to keep the footprint of the mill as small as possible while not limiting its capabilities too much. I also want to make it as self contained as possible and to have all the sensitive components such a limit switches, couplings, gas struts ect. tucked away so they will not collect wood dust and grime.

    I based much of my design off the excellent conversions documented here by the likes of gd.marsh and 91TSiGuy. Thank you all for the inspiration! I would especially like to thank 91TSiGuy for providing me with some of his CAD models to get me started.

    Below (hopefully) is a screenshot of the overal CAD model so far. I have not modeled the head since I am not making any modifications to it, yet.
    The control panel uses an elo InteliTouch screen I got on ebay and will have physical knobs for the most common controls, such as FO, RO, Joging and program Start and Feed Hold. Eventually spindle controls will be added, but are not in the plans at the moment. All the wires will pass thru the control panel swing arm and into the column, from whence they will go down into the stand were the electronics will be located.

    All the motors are direct drive and tucked in close to the machine to save room.



    Here is bottom view showing the mounting of the ballscrew bearing blocks and the motor couplings. It is a tight fit but results in a very clean and simple conversion. I will not be able to over travel as much as with the other designs where the bearing blocks and couplings are outside the castings, but that is not my goal and I still have more travel then stock. I have access to bigger machines if I need more travel.



    I know I will need some type of counterbalance on the head to keep it from falling when power is cut to the axis motor, but i would like to avoid having gas struts or a counterweight on the outside of the machine as is the typical solution. Fortunately the column is just tall enough to allow placing two gas struts inside it, see below.



    My head weighs right at 200#, well, you know what I mean .
    I did some quick calculations using the gas laws and found that two of the 100# gas struts sold by McMaster produce about 180lbf while extending at free length (full extension) and require 301lbf for compression at solid length (full compression). This results in an average force of about 241lbf. I was hoping for something closer to 200lbf but without custom struts that is unlikely to happen so two 100lbf struts it is! I also figure most downward moves are at feed and most upward moves are rapids, and since the motor has more torque at feed speeds everything balances out nicely.

    Here is an ISO view of how the struts act on the ballscrew mount. The studs on the end of the struts are just a slip fit in the holes, but they won't go anywhere since they will always be in compression, unless I rapid faster then the struts can keep up with, which I doubt!



    I have to run, more later tonight, hopefully.
    I like constructive criticism, so if you think something will not work let me know!

    Thanks for looking!

    Kurt

  3. #3
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    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    Looking forward to this thread progressing. I have been on the edge of ordering a G0704 but, i came across a lightly used Enco RF45 clone with DRO, and feed for $1300 so that Is what i bought. I will be heading to pick it up tomorrow or first of next week I hope. Plans will be for a CNC conversion but it may be a little ways down the road.

  4. #4
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    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    It looks like a very clean conversion you are planning, but I have a few comments.

    1. I personally have had issue with gas struts needing periodic replacement on various things I have with gas struts on them . As such, I would personally not put them inside the column simply due to access considerations. It appears that access would be limited to the access panel on the back of the column whic seems like it would be tight.

    2. If you proceed with the internal gas struts with the strut rod simply resting on the casting, I would provide a dimple or recess for the rod to locate on. You may have already planned this but it wasn't clear from the pictures.

    3. The location of Y-axis bearing block for the ball screw being attached underneath the base casting will mean that to access it you will need to have a hole in the table you use, or you will have to lift the machine. This is not ideal from a maintenance point of view. I realize that your design shortens the distance that the motor extends out the front, but I would make a design that allows easier access. On the X axis this isn't a concern since access is easy from below.

  5. #5
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    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    Mike, sounds like you got a good deal. I have used a G0704 and they are nice machines but I can assure you that the RF45 type machines are much more capable. You will not be disappointed. Is the machine you purchased one of the newer ENCO models with blue paint or one of the older grey ones? The blue ones seem to have better fit and finish.

    109jb, you make some good points there. You are right that the struts will likely require periodic replacement, but they are actually very easy to get in and out of the column, however I do have a hole in the table which helps.

    I have been spending most of my time on the conversion and actually have the Z-axis operational, though not quite finished. To install the struts I raised the head to the absolute max and then slipped the strut in place and marked how much length needed to be removed for the rod end of the strut for it to just slip over the ledge in the casting. This ended up being around 3/8" which I parted off on the lathe. I then slipped the struts in place and positioned the lower end so they would bear as I liked on the casting. I then lowered the head about .1" to put the struts in compression and adjusted the limits so I would not accidentally move up so far that they would come loose. I was planning on putting a dimple for the ends of the struts to rest in as you mentioned, but even my small right angle drill can't get in there to make it, and with my limited testing it does not seem like the ends of the struts are going to go anywhere.

    When the time comes to replace the struts all I have to do is override my limit and move the head up until the struts are free and slip the new ones in. I certainly had my doubts about having the struts in the column but so far it looks like it will work OK.

    I guess I should have checked here earlier! I just finished drilling and tapping the holes for the Y-axis ballscrew bearing in the base casting. Access is a little tight but I have a good sized hole in the stand which helps a lot. Maintenance will be more difficult, but hopefully it won't require as much since it won't be exposed to coolant and chips.

    Here is the large access hole in the base. Plenty of room to work here!


    Thanks for the replies! It is greatly appreciated.
    I'll see if I can get caught up on post tonight.

    Kurt

  6. #6
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    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    The Enco I bought is blue kind of like yours. The only date i could see on it was on the motor which states 2011 but that could just be the build date of the motor. It may be next week before I go get it being we have some weather heading our way. I looked through your photos and I am pretty sure I will not go through the beautification mods which you did but I sure do want to do the oiling and CNC mods as soon as funds are available. BTW, My machine came on a stand but I sure like that yellow pine table you built for your. That is some fine looking woodwork from the pictures.

    Could you possible get me a measurement? I was hoping to not have to trailer machine home but I think even off the base the mill is just too tall to fit under the camper shell on my truck. With the Z axis moved all the way down what is the total height from the base to the top of the Post? I only have 36 maybe 37" clearance if i want to leave the mill upright. I found that the mill is about 48" tall but that spec had the Z axis fully raised and the motor is pretty tall.

  7. #7
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    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    Your CAD model is looking good.
    You probably only need 1 strut if your intent is to keep the head from falling when powered off. These dovetail columns have alot more friction than you think, especially due to the cantilevered mass of the head. My IH clone doesn't fall with power off (5tpi ball screw) and I do not have any gas struts. If I loosen the gibs and press down on the head I can make it fall but barely..
    Also, to keep the bottom end of the strut from walking around, why not put in a thin plate with a hole to locate the strut, with the outer edges of the plate constraining it inside the column?
    For the Y axis - check that the ballnut isn't going to restrict the movement of the saddle away from the column. I recall having to open up that little bit at the front of the base to get even front / rear travel with the ballscrew in place. The ballnut is larger than the original bit from there.
    Attachment 347182

    Mike

  8. #8
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    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    Mike Hall, the base to column height is right at 43", so looks like it won't fit under your camper. These machines are heavy enough to be a pain to move assembled, but are straight forward to take apart into manageable chunks and is what ENCO recommended. I have moved mine this way on my own and I'm a small guy. For your purposes I would suggest taking the head and column off. A small adjustable wrench will do for the head, you'd need a 12mm hex key for the column. There should not be any shims or anything that will be hard to get back in place.

    Thanks for the complements on the stand! It is rock solid and cost all of about $7. I think I got it out of one 2"x10"x10'.

    ninefinger Mike, I did consider using one strut but could not figure out a symmetric arrangement to prevent putting a moment on the slide or ballnut mount, though that probably would not mater. I like the locating plate idea for the strut ends, just might have to implement it. Thanks!
    I just cheeked and looks like I will need to extend the slot in the base casting to get full travel. I guess I'll pull out the jig saw .

    Kurt

  9. #9
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    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    Here are some more CAD screen shots.

    General view of the X-axis ballnut mount. Note the four tapped holes in the front of the base casting which are for mounting the Y-axis ballscrew bearing.



    Underside of table showing method of mounting X-axis end bearing and slots in saddle for allowing some transverse adjustability of the ballnut mount.



    Tapped thru holes in end of table pockets for mounting end bearing. I would like to avoid these but they are neat so don't bother me to much.



    Some details of the Z-axis parts.



    I'll be putting all of the CAD files in this Google Drive folder in the next few days.

    https://drive.google.com/drive/folde...1k?usp=sharing

    Thanks for looking!
    Kurt

  10. #10
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    ENCO CNC Conversion - Axis Motors

    As I mentioned in the first post I purchased the the axis motors and ballscrews at the end of the past summer.

    After much deliberation I decided to use closed loop steppers. I was originally planning on using regular steppers because they are inexpensive, but I realized that on a machine this size I would need biggish steppers to avoid loosing steps and those are not all that cheap. So I toyed with using servos. The motors themselves are not all that expensive but once I added up the cost of encoders, drivers, belts and pulleys it well exceeded my meager budget. Also I was having trouble designing a servo system that was as compact and as simple as I wanted.

    I ended up purchasing the following SuTai brand closed loop steppers and drives from a company I found on Alibaba.

    2X NEMA 34 1200 oz-in Stepper Motor w/ 1000 line encoder Model# 86HSS1402
    1X NEMA 34 1600 oz-in Stepper Motor w/ 1000 line encoder Model# 86HSS5001
    3X 8.2A Closed loop stepper driver Model# HS860

    The motors and drives are made by the Changzhou Sutai Electrical Co. and appear nearly identical to those made by Leadshine, they even sent me Leadshine branded software and documentation. The total cost including shipping was about the same as a basic 3 axis stepper kit from ebay, and arrived in about 3-5 days. At first I had trouble getting my computer to communicate with the drives, but costumer service was fantastic and I got the problem resolved very quickly. This was my first time purchasing direct from China, so far so good!

    Here is a picture of the motors during preliminary bench test with an Arduino running GRBL. That laptop is my CAD workstation


    About ballscrews next..

  11. #11
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    ENCO RF45 CNC Conversion - Ballscrews

    I decided to go with the standard Chai fare ballscrews with double ballnuts and to use RM2005 on all axes.
    The screws are very decent quality, though I may need to replace one of the ballnuts since the races are starting to flake and it is not even in use yet.

    Hers is a picture of the ballscrews. I had forgotten I made the Z-axis ballnut mount before receiving the screws. More on that soon.


    Another view


    I have attached my ballscrew drawings for your reference.

    I am trying not to get boring with details but still provide enough information, let me know if I should change anything. Also, would fewer or more pictures be better? I have plenty.

    Thanks for looking!

    Kurt


    Disclaimer: Unless your machine is identical to mine (which it is not) and you convert it exactly the same way (which you won't) screws made to these drawings will not work!

  12. #12
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    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    Looks awesome, I can not wait to get to this point with my Enco Mill. I guess I should be content with just getting the Mill home first.

    What I would like to see is a list of all the components your using on your build. I have been looking around getting ideas of what I would want to use for my conversion and a nice complete list would be great for comparing with other builds or components I may find good deals on. A master list is kind of what I am talking about.

    What are the chances I could score the 3d model of the Mill without the CNC mods added? What software are you modeling it in? I am a Autocad user for 20 years and i find it hard to migrate to anything else. I have trouble leaving all those key commands and i find myself getting irritated trying to do simple task in other programs. If you would be willing to share that model let me know. I would enjoy messing around with some ideas for my CNC conversion as well.

    Mike

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