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View Full Version : Newbie Looking for Advice (Sherline or HF Conversion)



Deviant
09-23-2004, 01:17 PM
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
09-23-2004, 02:09 PM
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
09-23-2004, 02:39 PM
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
09-23-2004, 03:08 PM
$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
09-23-2004, 03:26 PM
Is there additional cost for the drive box for the steppers?

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

xknacx
09-23-2004, 03:42 PM
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
09-23-2004, 09:14 PM
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
09-24-2004, 08:29 AM
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
09-24-2004, 08:55 AM
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
09-24-2004, 09:52 AM
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
09-24-2004, 11:15 AM
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
09-24-2004, 11:25 AM
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.

kdoney
09-24-2004, 02:40 PM
XKNACX:
"I am a Gates distributor"

How about some discount for your fellow CNCZONER's?

kdoney
09-24-2004, 03:01 PM
I believe FPWORKS has given you a good starting point. I have a mini mill cnc'd. It is a speedway with a custom ballscrew stepper setup and it works fine at slow speeds. For instance, I had to run for 30 minutes to do a 1.5" mill circular pocket into .128" 6061 aluminum with a .375 end mill. No hole, just plunging into the workpiece. The feed was .004 and the speed was 10. This was the safest I could find with my double stacked steppers (nice and expensive) and gecko 201 drivers (nice and expensive). I also have a cnc Sherline 2000 with single stacked stepper and 201 gecko drivers and I find the size and speed limitations infuriating. If you have to move your workpiece AT ALL, it will cost you at least 10 minutes of moving and measuring. Just the run time was at least 3 times longer. So the same hole with the Sherline setup would be 1.5 hours. That's a long time to sit by a machine and watch for major errors. It may not seem like a long time now but every minute you are running you're sitting there watching and waiting.

Deviant
09-24-2004, 03:22 PM
Was the speed limitation based on the depth of the cut, or fear of breaking the bit.

This is all a new adventure to me, so the time it takes to cut something is unknown.

I just tried to call harbor frieght to get a price tag for local pickup on one of their mills. The lady at the counter stumbled around, then hung up on me. (lol)

Guess I'll swing by and look at the mill after work.

I wish I could fully understand all the items in FPWORKS's post, however in truth it just confused me. (grins)

I really need a good book/dvd on machining and specifically cnc machining.

kdoney
09-24-2004, 08:50 PM
Most of the fear you have with a stepper system is fear of losing steps. In the middle of a cut or a workpiece it could be disaster. Oblong circles and short straight lines are something hard to correct. Being relatively new to this myself (2 years) I would rather be bored for 30 minutes than scrapping a piece and having to start over. My frustration with the small envelope and the slow feed led me to move up (?) to the mini mill. It's all relative. If the pieces you want are small enough or you have enough patience to reposition your work many times you can be happy with the Sherline. It is precise and can be adjusted to a remarkable extent.

fpworks
09-25-2004, 02:25 AM
Sorry to be confusing! Ther is no way I can explain all that stuff without writing a book, so I really think you should try to figure out all that stuff out so you can really understand what what need vs what you want vs what you want to spend :) For stepper motors, I would suggest reading the "white papers" at Gecko's website under the support section.

http://www.geckodrive.com

Then I would try some searches on this site and some internet searches, hoping to find some technical papers that cover all the bases. Speaking to a vendor over the phone may be helpful.

You say you're not worried about speed now...just wait ;) hehe

Justin

imserv
09-25-2004, 08:13 AM
First, a Sherline cnc setup.

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

Cost is an issue, secondly space.



Since no one has addressed your first option, I will make a few comments.

The Sherline, is a CNC ready machine. It has nema23 motor mounts, thrust bearings, antibacklash nuts, and flex couplings already installed, and can be setup and running in about an hour. It's also available from stock.

Add about 15 minutes additional to bolt on 3 stepper or servo motors. You could be able to make parts in under 2 hours.

If you are not very mechanically inclined, retrofitting a minimill will be a daunting task, even with all the free support from fellow users and purchase of a "kit". Don't expect any help from the machine manufacturers, they don't speak your language or use your alphabet.

Just assembling the Sherline may be a daunting task, but your chances of success are very high since they provide such good support.

You, or any others reading this thread should consider what your hobby or machining needs are.

Do you want to learn about some aspect of CNC machine retrofitting, controller building, electrical assembly, software programming, etc, in your free time and eventually have a CNC mill, or do you want to make some parts or products next week?

The learning and playing with the machines, electronics, software and all the gadgets is fun for some and exactly what they want to do. For some others however, it's all mumbo-jumbo and their interest is in having a tool to create the tiny details on parts for scale model train, boat, car, engine, or whatever. Some want to make signs, computer sculpture, id bracelets or furniture.

The shortest route to making parts will cost more money but very little time. The least expensive machine, custom "do it yourself" retrofitted, may take several months or even years to complete, and will have a higher probability of never making any parts.

There are many options available. Inexpensive servos are available. They can drive a Sherline at 50 inches per minute on all three axes and will not lose steps. They will also work well on a mini mill.

See this CNC zone thread for info on servos:DeskCNC servos (http://www.cnczone.com/forums/showthread.php?t=5533)

Fred Smith - IMService
http://www.cadcamcadcam.com

kdoney
09-25-2004, 09:03 AM
First of all, I assumed you where going to buy a cnc ready machine or kit from a reputable supplier. The reviews and packages I've seen are just as likely to give you adjustable precision as good as the Sherline. Secondly, you need to read alot before making a decision. How big of a piece you will be milling is important. I would say to take any estimate you have and multiply it by 1.5 to get your minimum requirement. Please take your time. There are a lot of salesmen out there that believe they have the best solution. A cnc machine is not magical. You will still have to learn how to mill, design, draw, setup, measure, troubleshoot electrical and mechanical problems and most of all code your part (in gcode) even if you use a drawing to gcode converter. There are many jobs which don't warrant a cnc procedure and you'll want to just do it. At that time a mini mill with an R8 spindle will come in handy.

One last word. I've never met a machinist who wishes he had bought a smaller machine.

http://www.mini-lathe.com/Mini_mill/Main/mini-mill.htm
http://plsntcov.8m.com/grizzley.html
http://www.5bears.com/cnc.htm
http://www.cnconabudget.com/
http://www.billsbest.com/thatlas.html

Deviant
09-25-2004, 09:13 PM
Well ideally I'd like to make some parts, one day. (grins)

The majority of my items are pretty small that I'm looking to do... Most under 1.5x1.5x5 inches. ((really under 15mm round by 50mm))

Of course, you never know what you might want to build.

I stopped by at Harbor Freight today and looked at the 299 and the 499 mills. Both were looked pretty small.

How small is the sherline compared to those 2 machines? in physical size.

The more I look into this, the more I get confused. (lol)

kdoney
09-26-2004, 02:10 PM
A more expensive mill but about the same size as the HF mini side by side with the Sherline is at

http://www.billsbest.com/thatlas.html

Deviant
09-26-2004, 09:10 PM
The taig and the sherline are about the same size right?

hmmm maybe I will have to go with the homier mill. I was trying to find something with a standard conversion kit, as far as the mounts go.

Definately a learning experience.