What is the ultimate benchtop CNC mill?

[SND]

Hi,

I think this is my first post here. I need to know what the ultimate benchtop cnc mill is. I am limited in size because it has to make it down into my basement but when the time comes I want to get the best that will make it down the stairs. I already have a 1200 pound lathe down there and a benchtop mill/drill that will be kept manual.

I've seen Tormach's website. It looks pretty decent for the price but is there anything a little better or faster for similar size? What about the conversions like the dovetail column mill that industrialhobbies sells? These 2 seem to be the most capable benchtop mills I've found on the net so far. Are there any other brands or kits that may be even better?

I plan to run anywhere from 1 to low 100's of parts on it. Most of the work I do is fairly small. Usualy no bigger than 6" by 10" but I'd like as much travel as possible just incase the odd job comes along. Most of the work is aluminium.

Those of you who have bought the Tormach, how capable is it?
I guess even with only 65ipm rapids it would still be faster than manual machining.

thanks for any input on this.

[Neil_J]

...It doesn't exist yet They are all compromises.


I will be buying an RF-45 or clone, possibly from IH. The Tormach is nice but the table size/work area is tiny. Dont' forget the room you will need for tooling, clamps, fixtures, etc... It adds up quick.

[OwenL]

Originally Posted by Neil_J ...It doesn't exist yet They are all compromises. I will be buying an RF-45 or clone, possibly from IH. The Tormach is nice but the table size/work area is tiny. Dont' forget the room you will need for tooling, clamps, fixtures, etc... It adds up quick.

Does the RF-45 offer more work area? i thought the table size and max height was very similar between the two machines [Pcnc / RF clones]

Owen

[Neil_J]

Originally Posted by OwenL Does the RF-45 offer more work area? i thought the table size and max height was very similar between the two machines [Pcnc / RF clones] Owen

Tormach's travel is 16" x 10" x 16.25".

The Industrial Hobbies mill has a table surface of 39.5" x 9.375". Longitudinal travel is 30.125" (roughly double the Tormach). Z travel is 20" I think.

The RF-45 is 32" x 9-3/8" / 20-1/2" / ~15" (don't quote me on this)


The Tormach's travel is probably OK for most people. To add, it is absolutely more accurate out of the box.. No question about it. However, most of the stuff I will be cutting will be bigger than that. And the '45s can hold 0.001" with the right hardware.

Of all the machinists I've met, none of them wish they had a smaller machine

[SND]

Hi Neil,

Do you plan to convert the RF45 to CNC or will you keep it manual?

If you do turn it into a cnc machine do you plan to buy the cnc kit from IH or will you just shop for all the parts yourself and make your own set up ?

Thanx

[Neil_J]

Originally Posted by SND Hi Neil, Do you plan to convert the RF45 to CNC or will you keep it manual? If you do turn it into a cnc machine do you plan to buy the cnc kit from IH or will you just shop for all the parts yourself and make your own set up ? Thanx

CNC for sure. The IH kit is nice if you have the cash. Rolling your own is pretty easy if you do your research, and shop around. It would also be a lot cheaper.

My setup will be as follows:

Software:

• Mach3Mill cnc control program, $160 (http://www.artofcnc.ca/)
• Alibre Design Professional, $700 - (3d modeling, Solidworks clone)
• SurfCAM 2003 & Visual Mill Basic

Hardware:

• Industrial Hobbies square-column mill
• LoCoCNC Breakout board - parallel port interface. I helped design these, they will be released the end of this month. See picture below.
• Tormach resettable-Z R-8 tooling system - [8x end mill holders, 9x ER20 colletts, 4x drill chucks, dial gauge, granite block] (http://www.tormach.com/Product_TTS.html)
• Power drawbar for quick-change tooling
• Geckodrive 320's (http://www.geckodrive.com/product.cfm?pid=13)
• Rockford precision-rolled preloaded ballscrews, +/- 0.003 (http://www.industrialhobbies.com/Mer...&Store_Code=IH)
• Ballscrew mapping to eliminate +/- 0.003 error
• Servomotors (still shopping this one)
• 2 micron home/limit switches on all axes - a MUST for a true CNC - (http://web3.automationdirect.com/adc/Home/Home)
• Toolsetting probe for Z - Automation direct
• Relay-controlled flood and/or mist system
• 3-phase spindle motor
• Variable frequency drive for spindle
• Custom pendent with rotary jogging encoder
• ShumaTech DIY digital readout (http://www.shumatech.com/products/dro-350/index.htm)

I highly recommend all the brand-names listed above. Especially the breakout board and the Tormach system.

[BobWarfield]

Neil, you and I are thinking along very similar lines, but it looks like you're further along. Could you share a little more detail on some of your suggestions?

Specifically:

On the Home/Limit switches:

- Will you use both home and limit switches or combine the functions?
- Where will you locate your home switches?
- Can you give a part number of other detail on the switches you propose to buy from Automation Direct?

On the tool setting probe:

- Part number or detail for Automation Direct?
- I keep wanting to read more about how to use these. Why would you need one if you have a constant Z-offset via Tormach tooling?

Custom pendant:

- Do share your thoughts, I'm in the midst of designing one.

ShumaTech DRO:

- How will you use this with your CNC system? Rogers has an interface that basically just uses the Mach macro pump to stop the machine if the DRO gets too far off where Mach thinks it is. Is that your plan?


- I would think a DRO would be useful in mapping your ball screw inaccuracies. Perhaps that is your plan? Are they accurate enough for this, or is that just what mortals who can't afford the laser setup have to live with?

Sorry to pepper you with questions, but as I say, you are very nearly on the same lines I'm on, hence it sparked a lot of my detail questions. Feel free to ignore some or all, and some probably deserve their own threads.

Best,

BW

PS Congrats on getting LoCoCNC going, or at least helping!

Originally Posted by Neil_J CNC for sure. The IH kit is nice if you have the cash. Rolling your own is pretty easy if you do your research, and shop around. It would also be a lot cheaper. My setup will be as follows: Software: Mach3Mill cnc control program, $160 (http://www.artofcnc.ca/) Alibre Design Professional, $700 - (3d modeling, Solidworks clone) SurfCAM 2003 & Visual Mill Basic Hardware: Industrial Hobbies square-column mill LoCoCNC Breakout board - parallel port interface. I helped design these, they will be released the end of this month. See picture below. Tormach resettable-Z R-8 tooling system - [8x end mill holders, 9x ER20 colletts, 4x drill chucks, dial gauge, granite block] (http://www.tormach.com/Product_TTS.html) Power drawbar for quick-change tooling Geckodrive 320's (http://www.geckodrive.com/product.cfm?pid=13) Rockford precision-rolled preloaded ballscrews, +/- 0.003 (http://www.industrialhobbies.com/Mer...&Store_Code=IH) Ballscrew mapping to eliminate +/- 0.003 error Servomotors (still shopping this one) 2 micron home/limit switches on all axes - a MUST for a true CNC - (http://web3.automationdirect.com/adc/Home/Home) Toolsetting probe for Z - Automation direct Relay-controlled flood and/or mist system 3-phase spindle motor Variable frequency drive for spindle Custom pendent with rotary jogging encoder ShumaTech DIY digital readout (http://www.shumatech.com/products/dro-350/index.htm) I highly recommend all the brand-names listed above. Especially the breakout board and the Tormach system.

[miljnor]

My home milling machine is the ultimate milling machine!

Just because it works and its in my garage!

GOT YOU! :P

I also wish I would have started with the Industrial hobbies mill But I had the HF clone so thats what I went with.

[Neil_J]

> On the Home/Limit switches:
> - Will you use both home and limit switches or combine the functions?

Ahh, that's one of the great things about the LoCoCNC breakout board. They are in fact combined; The + and - for each axis share a pin. Mach3 knows the difference based on which way the axis is traveling. In most cases, you only need one home switch, and one limit switch. Homing switches are always more expensive, since they are precision devices. AD has 0.0003" switches for $13 each.

The board supports both mechanical and optical (NPN phototransistor) type switches. I would recommend whatever type of switch you can find that won't be affected by coolant.

> - Where will you locate your home switches?

You can put them anywhere, esp. optical switches. I will be putting my Z home at the top for accessibility.

> - Can you give a part number of other detail on the switches you propose to buy from Automation Direct?

I'm still looking at this point. Right now I'm looking at the AAP2T14Z11 for $13. They are rated at 0.00039".


> On the tool setting probe:
> - Part number or detail for Automation Direct?

I'm still looking for one at this point.

> - I keep wanting to read more about how to use these. Why would you
> need one if you have a constant Z-offset via Tormach tooling?

The tool setting probe could possibly take the place of the Tormach system. Still researching this one.

> Custom pendant:
> - Do share your thoughts, I'm in the midst of designing one.

I will have two control boxes, an LCD-based panel, and a handheld pendant. If you look in the Yahoo Mach3 forums there is a guy with a system like this for his Bridgeport..

I could go on for a few hours about the two controllers, shoot me an email if you want to exchange ideas...

> ShumaTech DRO:
> - How will you use this with your CNC system? Rogers has an
> interface that basically just uses the Mach macro pump to stop the
> machine if the DRO gets too far off where Mach thinks it is. Is that your plan?

I will be using it for manual machining at first (my CNC conversion will take a lot of planning).. I will also be buying one for my manual lathe.

> - I would think a DRO would be useful in mapping your ball screw
> inaccuracies. Perhaps that is your plan? Are they accurate enough for
> this, or is that just what mortals who can't afford the laser setup have
>to live with?

Yep, I'll be mapping my ballscrews, Mach3 supports it. I'll also have the DRO before the homing switches, so it will be a good way to know where I am at, even if Mach3 closes/crashes. In my opinion you NEED seperate fixtures for complex jobs, all of which can be stored in Mach3. This is much better than manually resetting the DRO and feeling/touching your way to zero at the start of each job.

[wizard]

Hello everyone;

I have a couple of comments below.

Originally Posted by Neil_J CNC for sure. The IH kit is nice if you have the cash. Rolling your own is pretty easy if you do your research, and shop around. It would also be a lot cheaper. My setup will be as follows: Software: Mach3Mill cnc control program, $160 (http://www.artofcnc.ca/) Alibre Design Professional, $700 - (3d modeling, Solidworks clone) SurfCAM 2003 & Visual Mill Basic Hardware: Industrial Hobbies square-column mill LoCoCNC Breakout board - parallel port interface. I helped design these, they will be released the end of this month. See picture below. Tormach resettable-Z R-8 tooling system - [8x end mill holders, 9x ER20 colletts, 4x drill chucks, dial gauge, granite block]

• R8 is nice and all but I'd really like to see somebody come out with a taper on a small mill designed for CNC. I know this is dreaming at the moment but I would think that one of the existing tapers would work fine. It might be more economical to come up with a new taper specfically for small machines. In any event the potential for an automatic tool changer has to be part of the equation.
  
  Personally I haven't seen the Tormach system so I can't comment on that specfically.
  

  (http://www.tormach.com/Product_TTS.html) Power drawbar for quick-change tooling Geckodrive 320's (http://www.geckodrive.com/product.cfm?pid=13) Rockford precision-rolled preloaded ballscrews, +/- 0.003 (http://www.industrialhobbies.com/Mer...&Store_Code=IH) Ballscrew mapping to eliminate +/- 0.003 error Servomotors (still shopping this one) 2 micron home/limit switches on all axes - a MUST for a true CNC -

  I believe that this is a widely held misconception. Home switches do not have to be that accurate if your servo hardware can make use of the index pulse off the encoders. While certainly an issue with open loop stepper systems and the like, it is not a requirement in every case. Now at the low cost end, the various home out routines might not be supported via a given software and hardware package, it is something worth investigating for ones implementation.
  
  The other side of the equation with respect to homing switches, is that for some applications it does not make a huge differrence if the home position is off a few microns from own home out cycle to the next. On machines where it does make a differrence you do not often seee a reliance on high precision switches. Rather the home switch is there to tell the controller to look for the index pulse off an encoder.
  
  I suspect that you have already looked into what your software and hardware require. In my experience though precision switches are one of the most troublesome parts of a CNC machine. At least they where a few years ago when I was heavely into CNC lathe repair. The reality is that if your system can support other home out routines you will likely end up with a more reliable machine.
  

  (http://web3.automationdirect.com/adc/Home/Home) Toolsetting probe for Z - Automation direct Relay-controlled flood and/or mist system 3-phase spindle motor Variable frequency drive for spindle Custom pendent with rotary jogging encoder ShumaTech DIY digital readout (http://www.shumatech.com/products/dro-350/index.htm)

I highly recommend all the brand-names listed above. Especially the breakout board and the Tormach system.

I'd like to here more about the Tormach system. Frankly I've not been swayed by most other R8 quick change systems. Changing a R8 endmill holder doesn't take much time in my mind. Automated changing is another thing, that is why I'd like to see a small mill taper just for that sort of thing. A mini CAT taper is you will.

Dave

[Neil_J]

> R8 is nice and all but I'd really like to see somebody come out with a
> taper on a small mill designed for CNC. I know this is dreaming at the
> moment but I would think that one of the existing tapers would work fine.
> It might be more economical to come up with a new taper specfically for\
> small machines. In any event the potential for an automatic tool changer
> has to be part of the equation.

Aaron from Industrial Hobbies has converted a few of the square-columns over to ISO30 taper, and is also working on an automatic tool changer (table mounted, not carosel). This is one of the things that swayed me to buying an RF-45 clone.

> I believe that this is a widely held misconception. Home switches do not
> have to be that accurate if your servo hardware can make use of the index
> pulse off the encoders. While certainly an issue with open loop stepper
> systems and the like, it is not a requirement in every case. Now at the
> low cost end, the various home out routines might not be supported via a
> given software and hardware package, it is something worth investigating
> for ones implementation.

Believe it or not, the Breakout board that I helped design (pictured above) supports the index pulse function. I will be waiting to see if my servo encoders support it or not...


> I'd like to here more about the Tormach system. Frankly I've not been
> swayed by most other R8 quick change systems. Changing a R8 endmill
> holder doesn't take much time in my mind. Automated changing is another
> thing, that is why I'd like to see a small mill taper just for that sort of thing.
> A mini CAT taper is you will.

A good starting point would be the TTS datasheet. The bottom two pictures on the first page show a cross section that would answer most initial questions. There are a few reviews out there, one of which is at http://www.5bears.com.

I am still wondering if it is possible to make an ATC out of it, by using some CNC retention knobs threaded into the 7/16-20 hole in the tool ( Enco has these in the wrong size), and using a single-acting pneumatic cylinder and a grabbing finger to engage/disengage it.

[BobWarfield]

I like using an existing taper than you can find lots for an eBay.

Of course when automatic toolchanging comes up, you have to see these whizbangs:

http://groups.yahoo.com/group/minitoolchanger/messages

Best,

BW