Harbor Freight Mill

[MrRage]

I wanted to get this mill but before I do I wanted to ask you guys what you thought of it. Is it a safe buy, or am I better off skipping it and getting something else? There’s a new Harbor Freight store opening in town tomorrow so there should be some kind of grand opening discount I can use to get it
http://www.harborfreight.com/cpi/cta...emnumber=33686

[Bubba]

Mr. Rage,
I bought mine from HF several years ago and it is a true RF (at least it says so on the name plate). I have converted it to cnc and have been very happy doing so.
Realize No. 1 that it is a round column machine so that means you need to spend more time in doing your setup to get around the problems of moving the head for tool changes, but with a little foresight, it is not really (to me) a problem. It was a natural for conversion as the lead screw/nuts are junk. I had a problem with backlash (up to 1/4") prior to the ball screw conversion as the combination just got sloppy and no amount of tightening could reduce it. Along with this, the X nut would actualy slide in its mounting contributing to additional backlash movement. This was solved by "pinning" the nut to the table after alignment.
Depending on what you are going to cut, check out the actual required table movement. I have in a few cases been shy of what I really needed particularly in the Y axis. (after cnc, I get 7"). Rigidity of the machine is at best fair, but then again this is relative. What are you going to cut. If plastics or maybe aluminum, ok. I find it a little weak when trying to hog steel and ALWAYS be sure the column clamp bolts are tight. You will chase your tail if the darn column rotates at all with cutting action (again especially in steel with agressive cuts).
Bottom line, for typical work that I do it has been a good machine and for the price, if I was starting over again and know now what I didn't then I probably would do it over again IF I decided on a bench type mill.
Hope this helps.

[MrRage]

Well I'm looking at milling steel, ranging from mild tool steel to 17-4 stainless. Where did you get the ball screw setup from?

[trevorhinze]

Sorry to hijack your thread, but in his responce to your question Bubba stated that he had 7" of Y travel, and I wondered what he had to do to get that much travel. I bought one of these mills allreado converted to cnc (cnctools.net) and I only have 5.75 inches of Y travel, and I would love to be able to get closer to the 7inches bubba mentioned. As for the mill I love mine, but as I said I took the easy route and bought mine allready converted to cnc with ballscrews/servos/geckos etc, much the same setup that most of the conversions here seem to turn out with. The price was about 5700 delivered for the macine and controller and Mach2, but no computer. Good luck if you decide to get the mill.

[Mcgyver]

I wanted to get this mill but before I do I wanted to ask you guys what you thought of it. http://www.harborfreight.com/cpi/cta...emnumber=33686

+

Well I'm looking at milling steel, ranging from mild tool steel to 17-4 stainless[/url]

here's the other end of the opinion spectrum, from a home shop type cutting ferrous and non ferrous. maybe the work you plan on doing is so light this doesn't apply, but.....

I would not want work ferrous metals on a machine like this nor would i want a mill with a round column. I like quality tools that are a pleasure to use and cutting tougher materials on a light, poorly made (am i justified in saying that with .250 backlash :O) mill sounds like years of frustration ahead rather than pleasure. the round column adds to the negative opinion. Based on something as extreme as that backlash, I also have to question the quality of the ways, spindle, etc.

for me the decision is one of value not absolute $$$. for 1k US for that machine, I'd save my pennies until i could get into a used bridgeport, xlo or clone - . don't let the used part bother you, the backlash will be less than .250 Then you have the rigidty and horsepower you'll need. furthermore you'll appreciate the larger work envelope and most importantly larger spindle to table distance.

There is a reason why home shop machinists prize these 30 or 50 year old light tool room lathes and mills - its the way to get the quality & size you need to cut steel at a reasonable price.

no offence intended to peeps with those machines, obviously there are happy customers and creative types who make great stuff with them, nevertheless thats my call on buying one of those to work ferrous metals, esp when the price starts approaching the range of used full size mills.

[Bubba]

OK people, will try to respond to all the questions presented since I responder earlier.

Mr. Rage,
I purchased my ballscrews and nuts directly from Roton. (Be aware they have a $40 min per order)
I also ordered what I considered a set (2) of wipers for the ballscrews and only got one ea. (see my web site how I handled that one a heck of a lot cheaper)

Trevorhinze,
To get this, I "borrowed" an idea from one of the web sites I visited and was "cut" the front end of the "slot" in the base of the column slightly and was able to achieve a little extra travel in the Y axis. Based on measurements and "guestimates", the rear end of the second nut is darnd close to the front of the base casting when the table is all the way towards the operator (0" Y)

Mcgyver,
1. Yes, I work ferrous materials quite often and if things work out, you will see a picture of a "spanner wrench" cut out of 1/4" mild steel that I use on my ER collet system. This was done on my mill/drill and works very well. Yes, I used (comparably) slow feeds and speeds and a light depth of cuts, but I did it! After all, for me this is a hobby and not a job shop!

IF I had the room, I MIGHT have (knowing what I know now) have gone the route of a "bridgeport" instead of the mill drill. However, I am NOT displeased with the route taken.

As for the major backlash, I think this is in a large part, MY FAULT!, I had made power feed for the machine and in learning it and subsequently when cncd repeatedly ran into hard limit stops
I feel this contributed more to the problems than anything else. I also did some custom programming of TurboCnc and again several times in testing, I ran into hard limits at G00 speeds (NOT GOOD).

Round column..

Boy, this is a touchy subject.

IF YOU understand the parameters and are willing to live with it, It is not a bad system and sometimes can have advantages.
For instance, I wanted to mill out a drainage pocket located at the upper left end of the table. I simply rotated the head and milled away. Try that on a dovetail! I have a friend who has a full size mill that needed to rotate the head so he could attach the part to be milled to the side of the table (it was about 3' long) so he could mill on the end of it. I could not do this scenario due to the way my mill is mounted and has a drip pan in the way, but again this would be impossible on a dovetail mill. BOTH system have their positives and negatives.
The idea is "What are your trying to do and willing to live with"

By no means is this intended to be a "put down" to any camp. Would I like a dovetail mill/drill yes sometimes, would I like a rigid full size mill, yes sometimes. Am I happy with what I have, yes MOST of the time!!!

[miljnor]

Originally Posted trevorhinze
Y travel?
Sorry to hijack your thread, but in his responce to your question Bubba stated that he had 7" of Y travel, and I wondered what he had to do to get that much travel. I bought one of these mills allreado converted to cnc (cnctools.net) and I only have 5.75 inches of Y travel, and I would love to be able to get closer to the 7inches bubba mentioned. As for the mill I love mine, but as I said I took the easy route and bought mine allready converted to cnc with ballscrews/servos/geckos etc, much the same setup that most of the conversions here seem to turn out with. The price was about 5700 delivered for the macine and controller and Mach2, but no computer. Good luck if you decide to get the mill.

you Know that HF has two sizes of these mills. I have the smaller one and had to do what bubba did to get the travel. but the bigger one (the one he listed on the original post in this thread) has a listed y axis travel of 7.375"

# Drill capacity: 1-1/4"
# Face mill capacity: 3"
# End mill capacity: 3/4"
# Swing: 15-7/8"
# Spindle stroke: 5"
# Column diameter: 4-1/2"
# Spindle speeds (RPM): 120-200-250-290-400-465-820-1090-1245-1520-1820-2500
# Spindle taper: R8
# Longitudinal table travel: 19-3/4"
# Cross table travel: 7-3/8" <<<<<<<<<<<-----------------------right here
# Table: 8-1/4" x 28-3/4"
# Motor: 1-1/2 HP, 110 volt, single phase
# Angle vise capacity: 3-1/2"
# Height: 43-1/2"
# Shipping weight: 706 lbs.

its kinda silly they way they sell them I think the total price difference is like 200.00 dollars but the machine is way bigger than the normal bench top mills you see. Makes mine look like a wee midget!.

[Bubba]

OK, lets try the attachment again (third try

[Mcgyver]

1. Yes, I work ferrous materials quite often and if things work out, you will see a picture of a "spanner wrench" cut out of 1/4" mild steel that I use on my ER collet system. This was done on my mill/drill and works very well. Yes, I used (comparably) slow feeds and speeds and a light depth of cuts, but I did it! After all, for me this is a hobby and not a job shop!

Peace, hobby for me too, just offering a contrary viewpoint. of course you can do great work on it - a good carpentar never blames his tools. btw I can rotate the entire top of my xlo though, so haven't got me beat in the milling-out-the-corner-of-the-table department

wrench looks good

miljnor, one spec for vertical mills that is missing is the max space between table and spindle. people are usually concerned about work envelope but often this distance is the constraint

[MrRage]

Well I thank you all for helping me out on this.

After some careful thought I’ve decided to hold off on the mill for a few good reasons that you guys have helped me realize. If I’m am going to have to upgrade all the lead screws to ball screws then I’m better off look for a mill that already has ball screws. Because column sounds like it migh be an issue I’ll see what I can do about going with something else.

In the end I’m just going to save my pennies and see what mill might happen to come my way, or maybe even just build one. Building a mill that incorporates everything I want would be really cool but I doubt I have the resources or expertise just yet to do it.

[miljnor]

most manual (if not all) mills don't have ballscrews (that I know of) unless someone retrofited them. Don't dismiss leadscrews they are still quite usable and you can make them antibacklash with a little work (look at some threads on this formum). The biggest difference between leadscrews and ballscrews is the power transmitted to the table/workpiece (which can be overcome buy more motor/hand power) I THINK leadscrews transmit around 40% and ballscrew about 70-80% of the torque from the motor to the table. But don't quote me on this.


The column on the other hand is crap. I used one for years and hated it. God bless those with the patients to use them they are absolute saints, but the round column would be a deal breaker to me. Unless you want to modify it to a square column like Motomitch1 has done and I am currently doing, but this takes alot of work to do.

[Mcgyver]

Don't dismiss leadscrews they are still quite usable and you can make them antibacklash with a little work (look at some threads on this formum). The biggest difference between leadscrews and ballscrews is the power transmitted to the table/workpiece (which can be overcome buy more motor/hand power) I THINK leadscrews transmit around 40% and ballscrew about 70-80% of the torque from the motor to the table. But don't quote me on this.

that is a very good point, I wonder if people leap to the ballscrews thinking its defacto for cnc whereas for a lot of metal working machines the leadscrew might work.

I can see it has advantages, ie rapid traversing, or a higher speed operations, and would probably prefer to go that route myself....but perhaps the humble leadscrew is not given its dues.

A metalworking mill has high cutting forces. given that its the efficiency of the screw AND the pitch that are going to determine required torque, maybe a ball screw would actually require more torque, with the assumption that they are usually a bigger helix angle than an acme thread (aren't they?). ALso, the ball screw, unless its the expensive ground type does not equal greater accuracy and a ball screw does not equal zero backlash.