[Yavin]

I'm a student at the University of Colorado. I took their intro to machining course, and have since used the university's machine shop a number of times. I have been making parts which were relatively simple, but there are more complicated pieces (for instance, with circular profiles) that I'd like to make. I've done a good deal with electronics and more with programming. Given this background, I would like to purchase/build a 3-axis CNC and start making some more complicated parts. I've looked some into possible avenues, from modifying a Bridgeport-type or mill/drill to purchasing a dedicated CNC (Emco, Dyna Myte 2400). There are probably options I haven't even considered. Thus, I would really like some input from people with experience - What are my options, and what would anyone suggest doing? Are there any kits which are particularly good? Are there any dedicated CNC Mills which are particularly good in the price range?

My goal is to have a three- or four-axis CNC that can mill mainly aluminum (and a little steel). The maximum part size I hope to make is 12"x5"x5" (though a little bigger is obviously always better). I do not mind a big machine (I even looked into a Bridgeport), but I realize these are difficult to find at this price range, and I do only have single-phase power. I am a student, and I don't have a lot of time to invest in a big project (a couple of weekends would be fine, but a month-long project seems too long). I'm hoping to spend around $3000 for the machine and initial tools required, but would be willing to spend a little more for a four-axis CNC mill or a CNC to which I could add a fourth axis in the future. I would appreciate any suggestions and help you may have.

Intended Applications: making PCBs, making aluminum/steel pieces for cars/quadcopters/robots, making electronics housings (not just boxes, but more complicated structures), making models of various spacecraft, etc.

One last note: I do not care about brand names or new/used status (for instance, I'd be open to purchasing something through the auctions on this site), but I would like to be sure that upkeep of the machine won't be more work than machining the parts by hand.

Thank you for any help you can give.

Yavin

[awerby]

It sounds like a 2027 ER CNC Taig mill would be a good choice for you. They're solid and reliable machines built in the USA, with a 4th-axis add-on if you want it. The CNC function is available as a standard option; you don't have to buy a retrofit kit from another vendor. The highly-regarded Mach3 operating software is included. Milling aluminum and steel is not a problem, as long as you take it somewhat easy. The spindle's fast enough to deal with the small tooling used for milling PCBs. The maximum part size you indicate is about the same as its travels; it fits comfortably in Y and Z, but you'd need to deduct the tool radius from X, so you don't get quite 12" of actual part. With our discount, it comes in within your budget, with some extra left over for tooling.

Andrew Werby
www.computersculpture.com

[Winnfield]

It sounds like a 2027 ER CNC Taig mill would be a good choice for you. They're solid and reliable machines built in the USA, with a 4th-axis add-on if you want it. The CNC function is available as a standard option; you don't have to buy a retrofit kit from another vendor. The highly-regarded Mach3 operating software is included. Milling aluminum and steel is not a problem, as long as you take it somewhat easy. The spindle's fast enough to deal with the small tooling used for milling PCBs. The maximum part size you indicate is about the same as its travels; it fits comfortably in Y and Z, but you'd need to deduct the tool radius from X, so you don't get quite 12" of actual part. With our discount, it comes in within your budget, with some extra left over for tooling.

Andrew Werby
www.computersculpture.com

For a 12x5x5 aluminum part?

[DRock]

Due to your budget.

Your only other option would be to buy a G0704 and convert it with cheap components and cheap tooling for $3k.

[Winnfield]

I think that is a good option. I am amazed at what that little thing can do.

[zamazz]

Howdy, I'm in a similar position (I'm an aerospace engineer at Texas A&M) and I opted for a G0704. Of course, I'm already a machinist which really helps with the conversion. I've spent over 3k already and I'm not even close to finished. My build, of course is all out, with servos and linear encoders and such. If you were to order all your parts and just assemble it it would probably be around 3k, not counting tooling, measuring equipment, and other tooling. Both the Taig and the G0704 are good choices, but getting a CNC one and tooling and other equipment will be a stretch.

[Yavin]

Thanks, everyone, for the quick suggestions! I'm glad there's a good deal of consensus, and I'm really glad there is a good option at this price. I was a bit worried about the budget I'd allotted.

I was looking around at Taig cnc mills, and there seem to be three lines, with the following highlights:
2018/2019 for $996-$1099: Add your own controllers and motors
2026/2027 for $2250-$2446, with 4th axis option: Open loop, max. travel speed 30 ipm
3000 for $2995, with 4th axis for $700: Closed Loop, max. travel speed 100 ipm, max. cutting speed 60 ipm

Is there a notable difference between the performance of the closed-loop vs. open-loop systems? I realize that closed-loop control is great in theory (and has an impact on the max. cutting speed), but I don't know how much of an impact it will have on the finished parts themselves.

Also, Awerby, you mentioned that there was a discount. Is the discount offered if I purchase through taigtools.com, or through a particular distributor?

Thanks again for the helpful (and friendly) advice!

[Winnfield]

Try to think about the time it will take and the problems you will have machining something that is 12x5x5 on an 85lb. machine. You have said you wouldn't mind a large machine, yet you seem to be gravitating toward one of the smallest machines available. You can buy a G0704 mill and use it manually to make your own conversion, or get the BF20 version from machine tools warehouse, and it would be even easier because you can clamp mounts to the cast iron bosses on the machine, just like the factory kit. If you need a higher speed spindle, stick a Taig or Sherline head on the side of the BF20 spindle housing. The machine costs 1300.00 or so and you can run it with a g540 and some decent 320-380oz motors. You can do it for 3k if you spend it carefully and don't mind doing some of the work.

I converted a BF20 mill for less than $3K recently using parts off ebay. It was just a bunch of work.

[awerby]

Whether or not one can make a certain-sized part on a particular machine really depends on the configuration of the part and the tooling required to deal with it. Obviously, it would be difficult to cut all the way to the bottom of a part that's 5" high on any machine - most tools aren't going to reach, and to clear the high areas with the tool, you'd need enough headroom. But, especially if you can re-fixture the part without losing registration, or use the 4th axis to reposition it, you can often reach the parts that need to be cut one way or another.

As far as the Taig mills are concerned, you seem to have a pretty good handle on the various options. The DSLS closed-loop controller isn't a servo system, where any positional errors are corrected on the fly. It's essentially a stepper with an encoder, which will stop if it gets too far off of commanded position, triggering a reset in Mach3. When that happens, you need to re-zero the axis that faulted, so it's good to establish a reference point to go back to. But it can stop a lost-steps error from ruining a part that you've got a lot of time and/or money in, so it's worth considering. It is a little more temperamental than the open-loop system, though, and will occasionally throw an error when the tool hits a corner, or a knot in wood, or if there's an insufficiency of lubrication. The quality of the parts produced is pretty much the same whether you cut them slowly or faster, with the possible exception of wood parts, which can sometimes show dwell marks if cut too slowly.

Taig Tools and their sister company Microproto, which produces the CNC systems, sell their products at list price, except when they have a special promotion. Some of their distributors, such as myself, sell them at a discount.

Andrew Werby
www.computersculpture.com

[Yavin]

Try to think about the time it will take and the problems you will have machining something that is 12x5x5 on an 85lb. machine. You have said you wouldn't mind a large machine, yet you seem to be gravitating toward one of the smallest machines available. You can buy a G0704 mill and use it manually to make your own conversion, or get the BF20 version from machine tools warehouse, and it would be even easier because you can clamp mounts to the cast iron bosses on the machine, just like the factory kit. If you need a higher speed spindle, stick a Taig or Sherline head on the side of the BF20 spindle housing. The machine costs 1300.00 or so and you can run it with a g540 and some decent 320-380oz motors. You can do it for 3k if you spend it carefully and don't mind doing some of the work.

I converted a BF20 mill for less than $3K recently using parts off ebay. It was just a bunch of work.

I have not firmly decided on a Taig. They look less rigid than others, such as the BF20, but there is a definite benefit to the machine coming assembled and ready to go. The BF20s look sturdier, but what effect would this have on my ability to machine? Would it be a longer lifetime, higher precision, ability to machine harder materials or something else? Thanks for all the information!

Awerby, thanks a LOT for that information - I certainly assumed "closed-loop" meant "servo," and that makes a lot of difference to me. I see that the implemented "closed-loop" control is useful for some people, but I don't think it's worth the extra money for me.

I would like to clarify that I'm not intending to mill a 5" deep slot, but rather, mill parts from blocks of said size (12"x5"x5" maximum).

[wizard]

I'm a student at the University of Colorado. I took their intro to machining course, and have since used the university's machine shop a number of times. I have been making parts which were relatively simple, but there are more complicated pieces (for instance, with circular profiles) that I'd like to make. I've done a good deal with electronics and more with programming. Given this background, I would like to purchase/build a 3-axis CNC and start making some more complicated parts.

That is good but there is a big gulf between purchase and DIY.

I've looked some into possible avenues, from modifying a Bridgeport-type or mill/drill to purchasing a dedicated CNC (Emco, Dyna Myte 2400). There are probably options I haven't even considered. Thus, I would really like some input from people with experience - What are my options, and what would anyone suggest doing? Are there any kits which are particularly good? Are there any dedicated CNC Mills which are particularly good in the price range?

The first thing that comes to mind is that you are a college kid so where would you put a Bridgeport? Further how would you move it around. Don't get me wrong a Bridgeport can be a a very good investment if you can answer those questions. Plus if you are patient and look around you can often find used ones dirt cheap. I'm just not sure a Bridgeport is an optimal solution for you unless you have already have a working solution for installation and moving the thing around.

My goal is to have a three- or four-axis CNC that can mill mainly aluminum (and a little steel). The maximum part size I hope to make is 12"x5"x5" (though a little bigger is obviously always better).

Actually that size puts you into a large mill. The smaller mills like the TAIG would be pressed to their limits.

I do not mind a big machine (I even looked into a Bridgeport), but I realize these are difficult to find at this price range, and I do only have single-phase power.

I wouldn't worry about single phase. Today electronics has made the concerns about three phase machines out moded as you can find Variable Frequency three phase drives, cheap, that run of single phase just fine. At least anything below 3HP is easily doable on Single Phase. Yes an extra expense but not a show stopper, especially if you get a bargain on a three phase machine.

I am a student, and I don't have a lot of time to invest in a big project (a couple of weekends would be fine, but a month-long project seems too long). I'm hoping to spend around $3000 for the machine and initial tools required, but would be willing to spend a little more for a four-axis CNC mill or a CNC to which I could add a fourth axis in the future. I would appreciate any suggestions and help you may have.

There are only a few possibilities. One is to look for used hardware. The other is to do a conversion on a G0704 from Grizzly or a similar machine. Carefully planned a conversion can be done in stages to fit your schedule.

Intended Applications: making PCBs, making aluminum/steel pieces for cars/quadcopters/robots, making electronics housings (not just boxes, but more complicated structures), making models of various spacecraft, etc.

Cool! One suggestion: buy your mill and then make a separate machine to route PCBs. PCB routing is specialized enough to justify a purpose built machine. The requirements of PCB milling is light making it fairly easy to build a machine for salvaged parts.

One last note: I do not care about brand names or new/used status (for instance, I'd be open to purchasing something through the auctions on this site), but I would like to be sure that upkeep of the machine won't be more work than machining the parts by hand.

This is hard to address but up keep should not be that much more difficult on a CNC machine. Lubrication and mechanical adjustments are very important though because you can't feel the state of the machine.

Thank you for any help you can give.

Yavin

Auctions! If you are looking for deals this is the way to go. Military and government surplus sales can often turn up some real bargains. Then you have business close out auctions like the ones DoveBid runs. Deals can be found but seldom on E-Bay. In fact many of the used equipment sales on E-Bay are the result of sales from these sorts of sources ( with a corresponding big mark up).

Cabin Fever is in a couple of weeks, they have a big auction but I often find that the prices are higher than I'd like to pay. Also you are often again bidding against dealers that have deep pockets.

Find a hackers space with the sorts of equipment you are interested in.

Buddy up! Sharing equipment can be a pain in the butt but there have been a number of successful coops. Generally the ones we hear about are woodworking related, but I could see a coop approach working in a bigger city.

Focus on a rebuild of a dead industrial machine. Assuming you can get it dirt cheap it might be worth putting the time and effort into a PC based control. Unless you are really good this would likely take more than a couple of weeks. Depending upon how serious you are this might give you a very capable machine. The negative is I wouldn't even suggest this during the school year.

Up your budget a bit and buy a ready to go machine from LMS, Tormach, Novakon or the like. A turn key machine, to address your stated desires, will put you well above the $3000 limit you have today. That may not be as bad as you think as this would be a long term investment. The problem as I see it is the stated working envelope that you have. 12" is a lot of travel as you really need more than 12" with roughly 2" added to each end. So you are talking X travels of 16". In this case is thinking about a 2" fly cutter or shell mill clearing both ends in a facing operation. That doesn't even get into problems with Z in small mills.

[wizard]

I have not firmly decided on a Taig. They look less rigid than others, such as the BF20, but there is a definite benefit to the machine coming assembled and ready to go.

TAIG sells fully functional machines that work out of the box. The low end Chinese hardware are often referred to as kits. Obviously you get a lighter duty machine with the TAIG, that has a much narrower array of possible cutter sizes to work with. Only you can decide if it is acceptable compromise.

The BF20s look sturdier, but what effect would this have on my ability to machine?

It really depends upon what you are doing! It may not have any effect or it may mean far longer machining times for the same processes.

Would it be a longer lifetime, higher precision, ability to machine harder materials or something else? Thanks for all the information!

If you follow the threads for the various small mills on this forum you will see that the Chinese machines can be turned into very nice machines. Out of the box it is more of a crap shoot.

Awerby, thanks a LOT for that information - I certainly assumed "closed-loop" meant "servo," and that makes a lot of difference to me. I see that the implemented "closed-loop" control is useful for some people, but I don't think it's worth the extra money for me.

It isn't worth it on these small machines.

I would like to clarify that I'm not intending to mill a 5" deep slot, but rather, mill parts from blocks of said size (12"x5"x5" maximum).

I think your maximum size is a little big for the TAIG. Others may disagree. You need to think hard about how the parts you expect to make will fit into the work envelope of the machine you buy. It isn't just the part either, work holding and tooling factor into the equation.

Beyond that any mill with an R8 spindle is a big advantage in my book. Also you can't dismiss the value in all of that castiron in the Chinese mills. However you have to accept the kit like status of the machines. The low end Chinese mills require a bit of input from the owners to realize their full potential.

[109jb]

Most of the time the overall machine travel needs to be quite a bit larger than the part you need to machine. For example, machining a part in a vise may limit Y axis travel because the back side of the vise hits the column, or the position of the fixed jaw of the vise leaves a lot of unusable travel. This is especially true if you use keys on the vise to position it quickly.

For the size you have mentioned. You also have to consider what your machining process is like. If you are machining a 5" wide part and need to clean up the periphery with an end mill of say 1/2" diameter, you need a minimum of 5.5" of y travel and then you have to position your part perfectly. In reality, to machine a 12 X 5 X 5 part, I would say you would need a machine with travels of 14 x 7 X and Y travel.

For the Z axis, you have to take into account the length of the tools you use. There is a big difference in length between a 1/4" end mill and a drill in a chuck, or a boring head. You also have to account for your part height off of the table. Say it is in a vise and on parallels. In that case the top of part could be 3 of 4 inches off the table. On top of that, part geometry and clamp blocks need to be cleared. For a 5" tall part, I'd say you need a good 10 inches of z axis travel.

So in my opinion, you would need 14 x 7 x 10 travels. That is a pipe dream for that Taig you mentioned. These travels are all possible with the G0704 and is probably the cheapest way to get those kind of travels.. The Y axis travel of the G0704 is only 1/8" short, but with minor modification you can get over 8" of travel. You can also do the conversion in stages by using the stock screws to start with and then converting to ball screws later. This would get you going quicker and then you could use the machine to make the parts you need for the following stages. My G0704 with ball screws and all of the controls I built for $950 plus the cost of the machine. $1200 for the machine plus $950 bring it to $2150, but then you have to figure a vise, some tooling, etc. $850 will only get you the very basics for tooling.

Hope tis helps.

[amyers]

yavin, check out hoss site www.g0704.com, he has all the info there on costs to convert the mill and like others have said though not directly, he has his phase 1 and 2 plans, phase 1 is for converting the mill using the stock screws. his parts are easy for us newbies to make and he explains how to install the parts thoroughly. the dvd's are packed with pics and videos. i wouldn't mess with the little taig either, too many limitations with it imo.