Harbor Freight 42976


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    Default Harbor Freight 42976

    Last Saturday I attended a Model Engineering Expo in Toledo Ohio. I ran into Rick of the famous Rick-o-matic fame and showed him pictures of my conversion of a Harbor Freight drill/mill to cnc control. He urged me to post pictures here. So here it is.

    Per instructions learned from these Internet forums, the first thing I did after bring home my model 42976 mill was to totally disassemble it right down to the basic screws. I found one thrust bearing assembled wrong and straightened it out on reassembly. While apart I removed all the burrs, then measured each piece and entered it into a AutoCAD 3d solids model. Then I'd plot out each piece and cut out the paper model and place it onto the actual piece to be sure I had made no glaring error. Once I had it back together, I designed the NC hardware to match the motors I picked up on e-bay. Then I went to a friends house who had an NC mill and we made the parts. Anyone who has a Harbor Freight 42976 Drill /Mill and is interested in the 3d solids model I'd gladly post the .dwg file to the downloads for them to download, if I can.

    I currently have the x & y axis designed and built and having a great deal of fun playing with it. The very first thing I did was engrave some fancy script of my son's name using a pen and paper on the bed. Next I have to complete the Z axis design and build it.

    While apart, I didn't like the mechanism they had to oil the table so I designed and built extensions for them. Now it is easy oil the table. The attached pictures show my method. It was amazing how much easier the table slides after proper oiling. It goes without saying guys, keep your machines well oiled.

    Dead Nuts

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Harbor Freight 42976-mill-jpg   Harbor Freight 42976-mill2-jpg   Harbor Freight 42976-drive-jpg   Harbor Freight 42976-drive2-jpg  

    Harbor Freight 42976-mill_dwg-jpg   Harbor Freight 42976-mill_dwg2-jpg   Harbor Freight 42976-oiler-jpg   Harbor Freight 42976-oiler2-jpg  



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    Gold Member BobWarfield's Avatar
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    Very nice!

    Can you show us any samples of parts made with it yet?

    Best,

    BW



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    Community Moderator JRouche's Avatar
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    Hey Mr. Nuts, very nice conversion, real nice. JRouche

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Nice conversion. Especially like the improvements to oiling. We made oiling impovements to some factory built CNC lathes a while back to very positive effect. Oiling should be on everybodies mind especially on a CNC conversion when you might not feel the lack of oil.

    So what is the plan beyond 2 D CNC?

    By the way thanks for the offer for prints, it is good to see the sharing.

    Thanks
    Dave



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    Yoy asked for some pictures of jobs cut with my mill. Actually there have been few as I am busy with other projects. However I have attached a couple of photos. One is a logo of my antique tractor club that I only tried on a scrap piece of acrylic and another of my wife's name also engraved into a scrap piece of acrylic. The I tried to include a photo of my screen to show the computer graphic of the only real job (a moon shaped piece of steel that limits the "float" on my son's tractor's hydraulic lift). It is made from 3/16" steel. It took about 1.5 hours as I don't know just how far I can push these stepper motors. The are NOT very powerful and the maximum speed I can get out of them is about 8 "/min with no load. Plenty for me, though as the table travel is only 4.5" x 9". So you can see I can go from min X to max X in just over a minute.

    I am using Art Fenerty's "Mach 3" software to drive the machine. I am very impressed with it and especially with the level of support he offers.

    Attached Thumbnails Attached Thumbnails Harbor Freight 42976-gv-jpg   Harbor Freight 42976-jpg   Harbor Freight 42976-tractor-jpg  
    Last edited by Dead Nuts; 04-26-2006 at 12:32 AM.


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    Default Thanks

    Thanks for the kind words



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    Thanks Wizard for the kind words also. Yes, I have been a machinist for ofer 30 years and oil is VERY important!
    Next, I am looking forward to attending the CNC workshop in Ill in a couple of weeks. Also I am looking forward to finishing the Z axis control.
    Also in the last pictures above, I tried to take a shot of my monitor. Sorry it didn't turn out very well. I don't know how to eliminate the horisonal bar when taking a picture of a CRT, I afraid. However the parts fit into a mating part perfectly. It was great to see my own NC cut the parts!



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    Hi Mr Nuts;

    Good to hear that all that experience is going to good use.

    I'm very tempted by the CNC workshop, but am pulled in a number of different directions around here. I've heard some good things about it on the web, especially here. I know a little bit about custom CNC controlers and old Bandits but may be a bit short on PC CNC controls. Interestingly a small CNC mill or engraver has been on my mind for some time, so I really appreciate your efforts here.

    Thanks
    Dave



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    Dave

    We also had bandit IV's where I worked. I am retired now and once you get CNC's in your blood it kinda festered there until you get something at home to "work" with.

    It will be my first "cnc workshop" also, but Rick of RickOMatic fame, assured me I would have fun.

    If you are not into controllers, look at Mach3 when you do get one. One of my concerns was the massive amount of electronics involved. With Mach3, a standard PC is your controller (the majority of the electronics). You only need stepper motors (or servos), and a breakout board. But that's all, not a lot of electronics to worry about.

    Karl



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    I just picked up one of these yesterday. Apparently this item is being discontinued and you can pick one up at your local Harbor Freight (if they still have one) for about $200. Thats not bad at all for the cash!

    Are there any upgrades people have done for this model that have worked out well? A fine control on the z-axis would be something I'm interested in. I'm also curious about improving the x/y accuracy.

    I'm looking forward to trying to convert this to CNC!



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    What did this machine originally sell for? I found a local shop that still has one but it's a floor model and his price is $250.



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    It was originally around $400, from what I understand. Most of the stores near me were sold out.



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    Member Halfnutz's Avatar
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    Neat! I have one of the "12 spd. drill mills" also, I got mine from Speedway. I use it for drilling and tapping. One thing Ive allways liked is the quality. Allmost no backlash, everythjing is tight, the motor and gear train run very smooth, its a nice machine to work with, although mine is still manual. Great to see yours CNC'd. I am curious how you will do the Z axis.

    Halfnutz


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    Mr. Nuts

    I also have the same mill and have owned it for 3 years and it is mainly used for drilling as I have a cnc mill that put the unit into semi retirement. You have inspired me to possible cnc my unit also, as soon as I finish cnc-ing a 9X20 Harbor freight lathe. If I may ask some specifics. You are running Mach2 or mach 3 with this mill. That the same controll software my cnc uses.

    What stepper drivers are you using, and what size are the stepper motors and did you choose to use the existing ball screws, probely that way I'll go initially (or did you use ball screws) and how is that going?

    I like the looks of your control box that is sitting on the shelf, any way you could shoot a close up and let me know where you picked it up. At this point, I have been using an AT desk styled pc case, and it takes up too much room!! I need to repackage my electronic is something like yours.

    I am also courious as to how to do the z-axis. Really like your lube system. Good Job!!

    Looks like you hit a home run.

    Take care and keep up the good work,

    Ron



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    Checked one of these out at the store today. The unit has actually been discontinued. They were selling the floor model for $200. It was a little beat up. Chuck was bad, table had surface rust, and the paint was a bit banged up. I could have had it for $175 out the door with a coupon, but I passed on it, because I just couldn't figure out how to make the Z axis precise. I like the XY on it, but not the Z. Also, while it has an MT2 spindle, it has no drawbar, so you're stuck using a chuck, which is less than ideal for milling.



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    Member Halfnutz's Avatar
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    Mine has an MT2 and a drawbar. Iit doesent come through the top cover, but there is one under the lid on mine at least. The lack of a fine downfeed is a definate shortcoming, for sure.

    Halfnutz


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    I was thinking you could make a clamp to go around the part of the spindle assembly that doesn't rotate it (sorry, not sure exactly what to call it) and then bring a bracket off of that and mount a digital caliper and then mount the other end of it to a bracket coming off the left side of the head casting somewhere. This would give you a good resolution Z depth measurement, but you are still lacking in the Z fine adjustment. It seems like by tightening up the Z lock lever that you can move it a quite small amount by then tapping on the downfeed handle, but it would still be a tricky operation to "dial in" .010" for sake of example.

    With regards to backlash, the machine I saw in the store had about .013" backlash on each axis.



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    Yep, it should have a drawbar, but perhaps the floor model did not.

    There is a Yahoo group dedicated to this drill/mill:

    http://groups.yahoo.com/group/drillmill/

    They have mods for a fine z-axis control that don't look too hard to implement if you don't mind doing the work.

    A guy there also has an interesting z-axis setup for CNC. He hacked on a ballscrew to move the z-axis. There is pic there, but you have to be joined to the group to see it. Its in the RCAZ photo folder.

    If you own one of these its definately worth the time to sign up for the group and take a look.



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    Quote Originally Posted by Dead Nuts View Post
    While apart, I didn't like the mechanism they had to oil the table so I designed and built extensions for them. Now it is easy oil the table. The attached pictures show my method. It was amazing how much easier the table slides after proper oiling. It goes without saying guys, keep your machines well oiled.

    Dead Nuts
    Nice!

    I'm looking at oiling options myself... and have some questions...

    Do you have check/metering valves installed?

    I assume the oil just gravity feeds? How fast? Does the oil level go down something like an inch every hour or so?

    Do you oil the quill as well?

    Thanks!

    -Jeff



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    Jeff

    The oilers are entirely gravity fed. I used semi transparent tubing so I can see the level in the tubes. I just oil once per day and it seem to work quite well. Some axis use much more oil than the others. Though I have never timed them. The Y axis oil runs out the side some and uses the most.
    No I found no oiler on the qwill.

    Karl



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