View Full Version : Buying my first cnc mill. Please help!


touser
10-29-2003, 07:21 PM
Hello everyone, I have been very interested in cnc for quite some time and have always wanted to buy a small cnc mill. I would like to spend somewhere between $2000-$3000 for a small benchtop mill capable of milling small items such as metal parts for r/c cars and making waterblocks for computers such as those shown here http://www.dangerden.com/mall/products_home.htm

If anyone can recommend a good machine for in the price range or possibly slightly over the price range it would be GREATLY appreciated!

NeoMoses
10-29-2003, 07:54 PM
I think I can offer some very good advice for you... :) I'll list these in order of preference.

First, you can pick up some nice used Bridgeport Series I machines for less than $2500. It'll be difficult to convert one to a 3-axis CNC for less than $3000-$3500, but you might get lucky... However, this solution is hardly a 'benchtop' mill.

Your next best bet is to get a dovetail Z-axis mill/drill like the one here: (http://www.lathemaster.com/HEAVYDUTYMILLINGMACHINE%207045FG.htm) The Rong-Fu versions of these mills have a great reputation, but they can easily go above $3000 for a manual machine. Also, these machines are still quite heavy, most this size are over 600 pounds. You can pick them up from Enco, Grizzly, and many other places.

Slightly less desireable, but still very capable are the same sized machines with a round column Z-axis. They're just a pain in the butt to re-index the head every time you have to move it. I would highly recommend the dovetail Z-axis over the round version, even for the extra couple hundred dollars.

In both of these machines, you'll want to find those that have the highest spindle RPMs, as you'll probably be spending a lot of time machining aluminum and copper with small endmills.

NeoMoses
10-29-2003, 08:00 PM
continuing... The next step down is for the Speedway/homier sized mills. these machines are much smaller, weighing in at around 200 pounds, but they can be had for around $500. I've seen some very good work come off of these, it just takes a little more time. Realize this: the smaller machine you get, the smaller cuts you'll be forced to take due to the reduction of rigidity of the machines.

Last, and the least stiff, will be the Taig and Sherline machines. These are very small machines, but also very pricey. They have one very large advantage, however... they can be purchased as CNC machines right out of the box. some people really like this, some would rather have a larger, stiffer, more powerful machine that they converted for the same price. It's all a personal preference.

I'll write more later. For now I'll let you do some looking around and see what you can fit in your place.

touser
10-29-2003, 09:35 PM
WOW. Thank you so much for all that information NeoMoses! I think what I want is either the Taig or sherline that you mentioned at the end. Mainly because I want something that is fully cnc that can be plugged into my computer and used out of the box. Also for the most part all I plan on making is the waterblocks like the ones I linked to in my first post which are mainly copper or aluminum, and for making custom parts for small hobby gas/electric cars. And whatever I have not thought of that is nice and small. I just don’t know which is a better machine, the Taig or the Sherline. Converting a larger machine to cnc would seem like the best route overall simply because it wont limit me to such small objects, but I wouldn’t even know where to begin on doing that and I don't really have the desire to convert one. So I guess my question now is which is better, the Taig or the Sherline?

dcd121
10-29-2003, 09:56 PM
Check this link
for sherline with servos.
http://www.imsrv.com/deskcnc/bench_top_cnc_systems.htm

touser
10-29-2003, 10:05 PM
Thanks for the reply dcd121. I don't really understand that site. Does sherline not sell their mills completely ready for cnc so i can just buy one and plug it into my computer?

dcd121
10-29-2003, 10:15 PM
This is a very new deal. I use deskcnc with stepper motors but they are offering a servo system that is run by deskcnc software .
Options seem to be:
1. controller and motor kit.
2. controller and motor package fully assembled.
3. sherline mill or lathe with assembled controller and motors.
4. sherline mill or lathe with the controller and motors put together and fully tested for a turnkey, plug and play system.

Thats the way I understand their offering.

touser
10-29-2003, 10:22 PM
Thanks again dcd121. Sorry if this may seem like a stupid question but is a servo system better then stepping motors? Also i would probably want option #3 if i was to get a system, and those options are from the website you linked to or are those options from sherline?

dcd121
10-29-2003, 11:04 PM
I will go out on a limb here and say that servos are better.
You are right that Sherline offers a turnkey system but it is stepper. Ultimately, the controller software is the biggest difference. I just pointed out a website that is related to your interest in small mills. I don't want to be dogmatic and say one is way better than another. I agree with you 100 % about buying a turnkey system whatever it is.

Regards

HomeCNC
10-30-2003, 12:21 PM
NeoMoses: He may not need to spend the extra money for the Z axis dove tail Drill/Mill. I do quite fine with my standard Enco Drill/Mill converted to CNC. I have about $2500 total in my conversion. Take a look at it on my web site. I have never had the problem of re-indexing the head. I just have never needed to move the head in the middle of a job. If you keep your tools closely the same length you don't have this problem.

touser
10-30-2003, 08:07 PM
Thank you everyone for the help i really appreciate it. It seems like the most bang for the buck would be to buy a larger non-cnc unit and convert it to cnc, but i would not even begin to know where to start. Does anyone know where i can find step-by-step information on how to convert some of the larger mills while still staying within or close to the $3000 budget total for the mill and all the electornics needed.

dcd121
10-30-2003, 08:27 PM
Heres another link for you to look at regarding bridgeport or enco
mill conversions. Plans $100, parts around $1500. I built their 4 x 8 router and know nothing about electrical so if I could do it anyone who will follow the plans exactly (no improvements, no changes, no substitutions) you will end up with a nice conversion.
This is only a suggestion. You will decide what is right for you.
http://www.machinetoolcamp.com/knee_mill_cnc.htm

Regards, Dave

NeoMoses
10-30-2003, 08:51 PM
www.cnczone.com has lots of good information... Lots of intelligent people there. :D

You should check out http://www.homecnc.info/, he's got lots of good information.

Although I never made a complete writeup of my conversion, I did take LOTS of pictures, so I can be of assistance as well. Here's the post where I sold my machine. It's got a link to a video and some pictures of the machine. Just let me know if you'd like to see more pics, I've got tons.
http://www.cnczone.com/showthread.php?s=&threadid=1275

I, too, think the best 'bang for the buck' is to convert a manual machine yourself. I can't believe how much money those sherlines sell for sometimes, especially as small as they are.

Converting a machine is not that difficult, it just takes some time. If you want the best performance, I would recommend first replacing the acme screws with ballscrews. This will likely be one of the more expensive upgrades, but I think it will be well worth it.

Getting power to the ballscrews on the X and Y axis will be easy, you'll just need to build some brackets to hold the motors. The only part of the conversion that might be a little tricky will be driving your Z-axis. It took me about 2 weeks to design and build my Z-axis assembly.

Good luck, and let us know what you decide.

NeoMoses
10-30-2003, 09:27 PM
http://fineartlight.com/cnc/

That's where my CNC machine went to live. Looks like it's still doing well, too.

touser
10-31-2003, 04:58 PM
Thanks again dcd121 and NeoMoses. I think i am going to try and convert something like an Enco. If i do i think just buying the plans off of homecnc would be my best bet and just use the exact mill he used as well. I am just not sure what the total cost of everything would be.

HomeCNC
10-31-2003, 10:58 PM
Touser, My cost is what I stated above. Including my Drill/mill I have about $2500 in my machine.

BUT!!! I did not have to buy a PC, or software (CAD/CAM) I did purchase the controller software. I got most of my aluminum material from the scrap bin at work.