Harbor Freight Mill/Drill Conversion Log

[Halfnutz]

Bought new HF33686 and was horrified at vibration, chatter and noise durring heavy metal cutting. I figured something was wrong with unit but after tearing head down isolated problem to basic design, inherent in all machines, probably all versions(comments on this?).
Noise was coming from under pulley. I thought I needed a new spindle or yoke, its called the "spindle taper sleeve" HF part no. 6. Grizzley Part No. 306. I talked with service dept. at HF and they are clueless. so called Grizzly and told them I bought a used G1007 and got on the phone with those guys. This is a trick Ive used with my HF 9x20 Lathe and a couple other HF tools. The guys at Grizzley Know alot about these machines,the HF guys are just not real familiar.
Anyway fix is a $3.00 10 minut monthly maintenance item. Pack that Mo Fo full a greeze. I covered the spindle end, the spline, with some sticky red grease and packed the tapered spindle sleeve full from underneath with the quill droped down. This may be able to be done from above through the top of the pulley, but I allready had it apart so I went up & in from the front. COMPLETELY DIFFERENT MACHINE NOW. It runs smooth and has very little chatter. I dont know if everyone just tolerates the machines like it was, or if mine was unusually bad or what, but at Grizzly they told me all of the machines are like that -"real noisey". Man what a difference. Next item is ballscrews. I cant deel with the slop in the table. Then the CNC conversion. I will post all with lots of photos as I go.
Note: Pulling head apart was nothing. It was very easy to drop out the spindle and re-assemble in less than a half hour.

[HomeCNC]

I did not have any vibration problems with my Enco mill/drill on all speed except the upper two. I solved my vibration problems by using the power twist belts on the pullys. Now I can have the spindle all the way up to 2000 RPM and the shaking is gone from the table.

[Halfnutz]

I got the v-belts on order also every bit helps, but the problem I was having was more noise and chatter than vibration, only in steel. it was just hammering away, under the pulley. Do you have play in your spindle(rotational/). I have also found that all of the noise and chatter is probably due to my ineptness more than anything else. By changing spindle speed most of the vibration can be removed. I have lots to learn about cutting speeds in different types of metals, tool selection, cut and feed rates etc.

[Halfnutz]

Grease has really not entirely pleased me so I went back into head and tightened up bearings in spindle. This was done by tightening a retaining nut and lock nut on top of bearing assembly. Machine runs very smooth. There is essentialy no vibration at all, even cutting CRS. I am pleasantly suprised at how smooth and powerfull this thing is. Here are pics of head tear down

[Halfnutz]

Bolted unit down to floor and greatly heped with problem. Machine runs really smooth now. Ordered ballscrews to begin conversion.

[HomeCNC]

Good luck with your conversion.

[smallplanes]

Does anyone sale plans or a kit for a cnc conversion on this machine? What will it cost for a full conversion ready to cut metal? I just bought a machine just like this one form Harbor Freight Tools.


Thanks
smallplanes
S.C.

[sin-city-custom]

What is a CNC conversion? I have no lathe experience except with drum and rotor lathes.

Thanks,
Dave

[Halfnutz]

(SmallPlanes) Ive found one ready to run bolt on kit, just do a search "CNC Mill/Drill Conversion" and you will find it and some others. A ready to run machine is around 10,000 and the kit for your machine is around 5,000 I think. If you do the majority of the work yourself it can be done for 1500 - 2000. depending on the way you go. Software alone can cost 2000. These machines require a ballscrew conversion for any kind of decent performance then you need steppers or servos and encoders, a controller hardware box, the stepper/servo drives, a power supply, the cabling, a computer, CAD and CAM software and then the custom machining, pulleys, bearings and motor mounting hardware. Its definately not a weekend project, unless you got the 5000.00 for a complete kit. If you got 10 grand for a machine I think it would be foolish to spend it on one of these, get a Enco or Jet Bridgeport clone and convert it. Thats just my humble opinion. Im doing it for the fun and learning, and my budget is tight, so this is the way to go I think. (SinCity) If you want to see a machine in action check out Jeff's site at www.homeCNC.com and run the movie file. He has nice plans for sale and some hardware also. Here is a pic of my home made flood system made out of a garden sprayer. It works great. (Response to next post added on 2/25) The coolant I am using is Sta Lube Soluable oil which is a mineral/vegetable oil base in an emulsion. Its cheap, about 5 bucks a quart and gets mixed up to 50/1 Im using it at 20/1. I never thought about it going bad, but I bet it could! Ill have to use it up quick. I also put a small hole in the corner of my table to drain the stuff into a small bucket. I really like the set up, the paper clips hold the thing in any position and its adjustable for both spray pattern and flow rate.

[HomeCNC]

I like your coolant system! That is one thing I do need to add to my CNC mill/drill. The chips build up so fast and I'm tired of spraying WD-40 from the can

What brand of coolant are you using? I have read people here that had problems with coolant going bad with things growing in it. YUCK!!! That has made me affraid to try a coolant system.

P.S. Halfnutz... Thanks for plug on my plans.

[Halfnutz]

No problem Jeff, your site is a real inspiration, its what got me interested in this, I had allready decided on buying the mill and when I saw your site I was hooked.

Well, after going down every cost saving avenue I can think up I keep circling back to where I started. There are a million ways to compromise on this thing but only one way to do it really well. Ballscrews, Gecko drives, Servos w/ encoders, and a big power supply. Any deviation from this basic scheme really seems to cut performance significantly. I would love to use Kerk or some other type of leadscrew, but nothing has the high efficiency , linearity and performance of a ballscrew. There are a number of multi axis controllers available, but someone compared it to like having a full size truck with a 1.5 liter 4 cyl. engine. The Geckos have the power to really move the big 450oz/in motors along, the others dont. I'm not real clear on why steppers arent as good as servos, but they definately arent and they require encoders, another added expense, but worth it from my understanding. The only thing I havent settled on is the software and the power supply. I have heard people using Dos systems and others with expensive Windows based programs. Any feedback on software choice would be appreciated. Of course I would like to spend as little as possible, but I dont want to waste a lot of time learning something that will ultimately have to be abandoned. I had ordered ballscrews at one point, and then I changed my mind (fortunatly the same day so it didnt cost me). I thought I could find a less complicated alternative, but I dont think anything else will work well on the size mill I have. So its back to where I started, I will have to re-order them next week I geusse. Unless someone can tell me a leadscrew of some type will work adequately...

[Halfnutz]

Update -
Ballscrews are on order. I got a 6 ft. Rockford 5/8", 0.200" lead piece of screw stock and two pre loaded nuts on arbors with mounting flanges and wipers all for $300.00. I decided that I had enough to do machining the ends and getting the angular contact bearings and screws installed, so I opted out of building the pre-load assemblies. I could have saved $ 100.00 by making my own pre-loads, but then I would have to make a mounting flange and some kind of wiper assembly. I will get to do all of that on my Z axis anyway.

I have got the mills spindle bearings broken in just like some old leather boots now with around 14 machine hours on them, and I have the pullies set at 2500 RPM allmost allways. The finish at high speed verses lower speeds is significant, and the HF seems to love screaming along at full throttle. To re-iterate, it didn't come out of the crate that way! I couldn't stand it when I first turned it on it vibrated so bad! I re seated the spindle bearings by tightening them, and then backing off the pre load on them over a 3-4 hour run untill they are smooth, with no measureable run-out, but much tighter than the machine came shipped. Also a pair of link type drive belts to cut down some vibration, and really bolting her down to concrete tight. It runs very smooth and quiet, with no vibration and cuts steel like butter at the high speed setting now. I am overall pleased with its performance and can't wait to get the table tightened up!

I also broke down and bought a kit from Hobby CNC. It is a "complete" kit with three 200 in/oz steppers. It should suffice for my little Homier 12spd. and get me some practice moving the motors around and designing parts. Then once I get my big HF mill converted I can use it for my lathe. lI finally got DeskNC for DOS running on my old computer. I am blown away at how complicated this whole process is due to the myriad of different directions people have gone in. Oh well, I wanted a hobby to occupie some of my extra time and energy (but not this much money).... I just had no idea how much crap I was going to have to wade through.

Anyone using DeskNC? How about HobbyCNC's board? Any comments/suggestions would be appreciated.