Newbie Looking for Advice (Sherline or HF Conversion)

[Deviant]

Hello All,

I've read through a large number of the posts on the forums, so hopefully I won't be abused to badly.

With that said.

I'm looking to enter the world of machining, specifically CNC. I deal with computers/software/networks as part of my daily job, I feel very comfortable with that aspect.

However when it comes to the actual machining hardware, I feel like a lamb led to the slaughter. Although, I do have good mechanical skills.

Now,

I've been looking at 2 possible solutions.

First, a Sherline cnc setup.

Second, a Harbor Freight mini mill with a cnc conversion.

Cost is an issue, secondly space.

I'll be setting this guy up in my dinning room, so I can't get anything to big. As much as my wife loves me, I think it would make her snap. (grins) I'll also need to build an enclosure around the mill to keep the chips/fluids in hand.

I plan on machining mostly small aluminum sparts, under 4x4x10 easily. This will mostly be for prototyping, which could lead to some small production runs.

If anyone have any suggestions on a website to purchase dvds on machining, that would be great. I have a grasp on the general concepts, but I think seeing it would be a big help.

A list of 1st and 2nd picks for parts used on a HF cnc conversion would be great as well as detailed instructions.

Any other tips/help would be great.

Thanks,

[xknacx]

My favorite links are:

http://www.mini-lathe.com They have a section on mini mill at the top. GREAT starter info. Also try Littlemachineshop.com they have some good info and is a good source for tooling. They sell directions for a cnc conversion for the HF model.

I just bought a setup for my HF mini and here is the link. It looks very promising and the service so far has been great. I should recieve it in the next few days.
http://www.lowcostcncretrofits.com/

I also purchased some drives and belts from Gates so I can do a 5:1 reduction. I am a Gates distributor so it was cheap, and good stuff also!!

Good luck.

[Deviant]

Let me know how that kit works out for you.

I have a few more days before all my money is in hand. Once I get the money, I'm going to become pretty serious about picking a machine.

How much do you think it cost you for your mill+cnc.

Also how much do you think it runs for all the extra bits you'll need.

[xknacx]

$499 for the HF mill. $599 for the complete cnc setup. $50 in belts and drives. $350 in tooling (vise, mills, holders, etc) Dang, now that I list it out this thing ended up costing a ton!!

[Deviant]

Is there additional cost for the drive box for the steppers?

Does the 599, include everything or is it a partial kit?

[xknacx]

For 599 you get the drive box with power supply built in and 3 stepper motors. Everything you need. Plug and play. you just need to find a way to mount the stuff.

[Deviant]

I'd like to set the machine up with the 4th axis rotary table.

Can the 599 cnc kit handle the 4th stepper.

Is there any difference between the Homier and the HF machines.

One is 399, the other is 499. Does the HF machine come with more accessories? Assuming there is no difference.

I'm looking at:

Homier-Speedway Medium Mill for 399.99 + s/h
Complete CNC kit (drive/steppers/4th axis) $??
Rotary Table $??
Mounting Brackets for motors. $??

Do I need pulleys/belts? Or do the steppers attach directly to the lead screws? Do I need a certain ratio for the pulleys, if I need them?

I'm trying to alocate my money and make sure there aren't any "gotchas".

Can someone fill in the gaps?

Will the conversion handle being upgraded to ballscrews later? I'd like to do it now, but I think I maybe stretching my budget.

Thanks,

[Zaphod]

If price isn't an issue, and you're just wanting to essentially plug and play, you might consider getting a Sherline mill w/ a Flashcut CNC setup. It's small, fairly portable, and runs on your PC. We use this configuration in a small woodworking shop nearly 12 hours a day. Works great for us, though we're not machining much metal. But you're looking at spending at least $3k.

[Deviant]

Price is a pretty big issue, secondly it would be size.


I think I'm going to go with the Homier 399.99 mill. Unless someone can tell me what I get for the extra hundred bucks of the HF.

Now I just need to absorb all the info regarding the conversion to cnc.

Also need to truely learn the differences between the different stepper/servos and the boxes that make them go.

Still in the dark on some of those items.

Does anyone know if that cnc conversion listed above is the best deal?

[fpworks]

I just did a lot of shopping for servos or steppers/controllers/software to power my new ballscrew mini-mill. I already have a working stepper driven Sherline CNC mill.

I really wanted servos, but after lots of research, I realized that there is a "break point" in cost where a quality stepper setup can be better than a cheap servo setup. I decided to go with a stepper setup.

Familiarize yourself with the following...then you'll have to piece the puzzle together yourself ;-)

1. What feedrates do you require? (spindle rpm/cutting tool/material/etc.)
2. How much table "drive force" will you require? (check force vs speed...see #4)
3. Leadscrew pitch ("gearing" between your servos/steppers and table)
4. Stepper/servo torque/speed/current charts (series/parallel, what voltage?)
5. Will you microstep the steppers, or not?
6. Possible driver current supply
7. Bipolar or unipolar stepper drives? (check effects on stepper performance)
8. Power supply voltage (and does it "agree" with drivers and servos/steppers)
9. Software compatibility with operating system/serial or parallel port.

Of course there may be a couple others that I have forgotten. Once you "think" you know EVERYTHING about the above mentioned topics, you should be ready to purchase a control system. About every topic I mentioned ties into every other topic in one way or another, and in many ways. The more educated you become, the better decision you will make.

Consider support. If you piecemeal something together off of Ebay and various vendors, you will have difficulty getting help with troubleshooting. It may be worth spending a little more money and buying everything from one vendor, IF they will provide support.

I decided to buy a pre-built controller box. I probably could have saved $400-$500 by doing it myself, but I considered the time required to build the box myself and the possible irritation of having to troubleshoot hardware and software at the same time if something didn't work out (by myself).

Good luck, and sorry to say this, but you'll probably end up going over budget :-(

[Deviant]

If I can justity it, going over budget won't be to terrible.

Where would I look up the items you mentioned.

The spindle, cutting and feed rate, would depend on what I was working with and the tool used? Right?

If I'm using 6061 Aluimum and running a 3mm endmill cutting slots I'd have to go slower than bigger end mill, for fear of breaking the bit.

I'm honestly not terribly concerned about the speed. I can handl if the machine needs to run over night to cut something out. I'm looking more for precision/finish over speed. And even the finish isn't a terrible big deal, I have a shell tumbler that I can drop my parts into, for that last shiny glow.

But for the most of the items on your list, I have no idea what the mean. "Lamb to the slaugher, remember"

Is there a website, to clarify those points you made?

[xknacx]

599 IS ONLY 3 AXIS. they do not have a "budget" kit for 4 axis. Look at the site. They have a controller box for 4 axis. Also email them, they are very helpful. As far as brackets go, you need to make your own. Gearing depends on the motors that you use. I am using a 5:1 ratio using gates xl series belts and drives. If you go to their website and go under power transmission they have a download on design. It will tell you what size belt you need depending on shaft distance and gear ratio.

I bought the HF model because I could pick it up locally. The homier is cheaper but I would have had to pay freight ($110) and wait a week. Either one is a fine machine.

Keep in mind there will probably be a lot of trial and error. Just get a good setup and experiment with it.