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Chris Byrne
11th Nov 2016, 01:52 PM
I am wishing to do carry out a CNC conversion on a bench type mill. The Optimum from H and F (HM28V) is the likely candidate at the moment.
A lot of the discussions on forums here and OS seem to be dated and as a result some firms mentioned are no longer in business. Has anyone who has had recent experience with a conversion of this type able to shed some light on kit suppliers. I am looking for a kit that includes mounts, steppers, ball screws. I also need a kit for the electronic side of things as well. I don't wish to roll my own from components as I don't have the expertise on the electronic side of things but am quite happy to fit and connect the appropriate components. Does not have to all come from the one supplier.
Thanks.
chris Byrne

wbleeker
11th Nov 2016, 04:28 PM
No experience with that Chris, but have noticed the same as you! But I do have a Tormach PCNC 1100 if you want to have a look? And only half an hour away!
Will

Hornetb
11th Nov 2016, 04:50 PM
Will, how much was your Tormach in AUD terms?

In response Chris, I'm actually just finally heading down this path with an Optimum BF20L or Sieg X3 (I have both, but haven't decided which to convert yet).

I'm currently doing all the electrics at the moment and just building my controller box. My X3 came with a bunch of CNC bits and pieces such as a break out board, power supply, drivers and steppers. They are a chinese kit off ebay and to be honest, I'm not particularly impressed. I didn't buy them, they came with the mill. IMHO I would have gone for a 48v power supply, and steppers larger than 490oz but it essentially came free with the mill so I'm just going to build it and see how it goes and if I decide to then I'll switch out and replace bits and pieces.

My biggest gripe is the lack of wiring and technical information pertaining to the breakout board and the drivers. I just placed an order for a different breakout board from Homann Designs (Homann Designs!, Your preferred CNC Supplier (http://www.homanndesigns.com/)) for the sole reason that there is at least some support and documentation.

If I was starting out I would seriously look at his Gecko kits. If you want plug and play there is a lot of information and support for this stuff. The cost is actually quite reasonable and you know what your going to get. JMHO.

Regarding the actually physical hardware kits I'm building my own. Ball screws came with the X3 but will need the ends machining to length etc to suit my application. There are loads of info for the BF20L/G0704 mills, I'm not sure what the Grizzly equivalent of the MH28v is but the mill is slightly larger than the BF20.

Gotta run, will try to come back to this.

wbleeker
11th Nov 2016, 05:06 PM
Will, how much was your Tormach in AUD terms?

In response Chris, I'm actually just finally heading down this path with an Optimum BF20L or Sieg X3 (I have both, but haven't decided which to convert yet).

I'm currently doing all the electrics at the moment and just building my controller box. My X3 came with a bunch of CNC bits and pieces such as a break out board, power supply, drivers and steppers. They are a chinese kit off ebay and to be honest, I'm not particularly impressed. I didn't buy them, they came with the mill. IMHO I would have gone for a 48v power supply, and steppers larger than 490oz but it essentially came free with the mill so I'm just going to build it and see how it goes and if I decide to then I'll switch out and replace bits and pieces.

My biggest gripe is the lack of wiring and technical information pertaining to the breakout board and the drivers. I just placed an order for a different breakout board from Homann Designs (Homann Designs!, Your preferred CNC Supplier (http://www.homanndesigns.com/)) for the sole reason that there is at least some support and documentation.

If I was starting out I would seriously look at his Gecko kits. If you want plug and play there is a lot of information and support for this stuff. The cost is actually quite reasonable and you know what your going to get. JMHO.

Regarding the actually physical hardware kits I'm building my own. Ball screws came with the X3 but will need the ends machining to length etc to suit my application. There are loads of info for the BF20L/G0704 mills, I'm not sure what the Grizzly equivalent of the MH28v is but the mill is slightly larger than the BF20.

Gotta run, will try to come back to this.
Hornet
I bought it when the AUD was well over the USD at the time 7500 for the mill 1500 for the stand and then all the other bits and pieces like tooling and fourth axis from memory it was around 3000 freight and then 10 percent GST on top to our government, no import duty is payable and if you have a business you get the GST back!
Will

Chris Byrne
11th Nov 2016, 08:54 PM
Will.

Now that's a nice machine and I would love to have a look at it one day soon, won't be for a couple of weeks though.
It would be nice to have one of those but I have no way of justifying something like that, I'm just real amateur.
I will be in contact.

Chris

Chris Byrne
11th Nov 2016, 09:03 PM
Hornet.

Thanks very much for you reply.
I had a look Homann Designs and they look like they might have what I need.
I need to be able to go to a source (preferably just the one) and buy the kits I need to go from a mill to a CNC mill. I need someone with the knowledge to supply the correct size motors, ball screws, controllers etc without me have to do trial and error stuff. I will give them a call.

Chris

Hornetb
14th Nov 2016, 02:01 PM
Ok, just coming back to this.

There is a lot of support and kits for the BF20L/G0704 mills with regards to doing the CNC conversion. Lots of people have been there before and done it.

An example of a hardware kit is from Automation Technologies (High-Torque Stepper Motor, Stepper Motor, Driver, Stepper Motor kit, DC Servo Motor, DC Servo Motor kit, Stepper Motor Power Supply, CNC Router, Spindle, and other Components. Stepper Motor | Stepper Motor Driver | CNC Router | Laser Machine | 3D Pri (http://www.automationtechnologiesinc.com/products-page/g0704-kit/g0704-cnc-kit-set)) but I'm sure you have seen that.

Also quite a number on ebay etc, eg. a complete motor, controller and hardware kit here (he has various versions of the kit): CNC Conversion Kit for G0704 Z axis nema 34 and Y X nema 23 electronic | eBay (http://www.ebay.com.au/itm/CNC-Conversion-Kit-for-G0704-Z-axis-nema-34-and-Y-X-nema-23-electronic-/291932809412?hash=item43f88d28c4:g:198AAOSwCQNWb3sR)

None are what I would call cheap but I can see the value in just buying a kit and installing it. You will still need to machine some parts of the existing mill (to make room for the ball nuts etc).

If you do get your mill, buy it from a reputable company that will back you up if you have issues. Check your dovetails on the machine before you go too far and make sure they are in a condition you are happy with before you head down the conversion path.

Don't buy from Ausino Engineering. Personal recommendation.

pippin88
14th Nov 2016, 06:07 PM
If you don't want to DIY then I would recommend looking at purpose built CNC mill, either Tormach or one from China.

Chris Byrne
16th Nov 2016, 11:15 PM
Hornet

Thank you for you last response. With those couple of recommendations in you last post and the one for Homann designs in the previous one I should be able to piece together the necessary components. Between those suppliers I can get pretty close to plug and play, especially on the electronics side of things.
I intend to shop at Hare and Forbes they already have a lot of my money and I have never had any problems with them. I'm looking at the Optimum 28 that they have. I will grab it before I order any kits, so I can do a bit of measuring and ensure the ball screws etc will be the correct size.

pippin88
Its the electronic side of things that I don't understand and I'm not capable of wiring up that stuff hence the need for a kit were someone else has done the thinking in that department. I think I can make a reasonable fist of the rest of it. Wish I had the $$ for a Tormach. I'm not aware of any good reasonably priced ready to go Chinise CNC mills, I you have some in mind please post a couple of names or links as I would be interested to have a look at them.

Thanks guys for your help.

Chris

Hornetb
17th Nov 2016, 03:46 PM
Just be aware again before you purchase the 28 with CNC kits in mind, the MH28v is physically a different machine to the BF20L. The kits for the BF20 will not fit the MH28, the table size is different, Z column is different and it has different range of motion so there is a strong chance that the whole machine is dimensionally different.

The extra size is always a bonus, but you will need to determine all the measurements and sizing for yourself and fabricate your parts. As far as I can tell Grizzly has no equivalent of this machine, hence the penetration of this model into the US market means that few people will have done the conversion on this machine making the demand for CNC kits unlikely to be offered unless you can find someone offering it in Europe perhaps.

That said, conversion of either machine is the same and you can manufacture nearly every component needed on the machine and try to order your ball screws pre-machined to your dimensions. But this in not the plug and play option you were hoping for.

Hornetb
17th Nov 2016, 03:58 PM
The BF20 is an "ok" machine. I'm only just happy with mine. It has a major manufacturing flaw that i was not able to rectify with the seller (you can search this site for my story). In its current form it is completely unacceptable to convert, but it seems that many people are reasonably happy with the machines. The surface finishes I can get are "ok" but I am unable to get a perfectly trammed head. Using a boring head with a single point cutter at low rpm's reveals astonishing flex in the column :oo:

In order to get around the column dovetail issue, if I choose to go through with this machine for the CNC conversion, I will be milling off the dovetail on the column and installing linear rails. It was either that or buy a "spare" part column at about $450+ plus shipping and still be rolling the dice with regards to the quality. You can actually buy the entire column head, motor, spindle etc designed to mount on the optimum lathe for only $730 plus shipping. So you can see that I'm torn between what to do. Those extra parts could potentially be handy, but its still kind of throwing money at a pig of a machine. The linear rails will cost me a few hundred most likely, plus the machining necessary to install them (I don't have a machine big enough to do it), but at least I will know what I'll get in the end.

Anyway, that's my experience. Best of luck with yours.

PDW
18th Nov 2016, 07:53 PM
The linear rails will cost me a few hundred most likely, plus the machining necessary to install them (I don't have a machine big enough to do it), but at least I will know what I'll get in the end.

Anyway, that's my experience. Best of luck with yours.

If you go ahead and need some bigger stuff machined, drop me a line. We can probably work something out.

PDW

Hornetb
19th Nov 2016, 10:31 AM
Thanks very much for the kind offer PDW, I haven't forgotten that you have offered to help previously. I do really appreciate it.

I might send you a message soon as I would love to have a more experienced eye look it over and see if you have any different ideas as your experience far exceeds mine, so would be good to hear your recommendations.

There is the way I look at it, then the way a more experienced machinist looks at it. Hahahaha, the two views aren't that similar hahahaha :)

Chris Byrne
20th Nov 2016, 08:27 PM
Hornet.

Thanks again for your information and sharing you experience.
Im hoping that the MH28V is pretty similar to the BF30 which plenty have converted. As you say I may be doing a bit more work than I planned but as long as I can get the motors, controllers, power supply etc as a kit I should be able to sort the bearing blocks and ball screws out. I have seen so many kits that I'm getting a bit confused as to what is out there but I think I have seen kits for the BF30. I will do some measuring before I jump in. The MH28V weighs about 60kg MOR than the BF20, hopefully the extra metal has gone into the column. Your intention to covert to rails makes one wonder why they are not being manufactured that way in the first place, cost I suppose.

Thank again
Chris

bmanners
27th Sep 2017, 09:59 PM
Chris, did you convert the MH28? I have the same machine and would like to do a conversion as well. Any tips would be greatly appreciated.

Cheers Brett

Sent from my SM-G920F using Tapatalk

NGrimberg
15th Jan 2020, 06:29 PM
The mh28 looks almost identical to the G0704. As such, the general conversion scheme should be the same. The specs I found indicate that it is a tad bigger than the G0704 so you will have to adjust dimensions a bit, but stepper sizes and such should work fine.

BaronJ
15th Jan 2020, 10:14 PM
Hi Guys,

As some may know, I have a BF20L mill. One of the issues with it is that the square cross section column has most of one face removed and dovetails down each side. The head is carried on a bracket that slides in the gap created on one face of the column and is raised and lowered by a screw inside the column. The bracket is not a good fit in that gap and relies upon the dovetails guiding the head to keep everything square.

The problem that arises is the locks for the head bear on the gibb strip on the right hand side looking from the front of the mill. When the locks are tightened the square column casting compresses and twists the head slightly out of tram. This leaves the column very slightly curved and the dovetails curve with it. This causes the head tram to vary with hight up the column. A side effect of this is the column will twist under a too heavy a cut, this can be seen as the head shaking from side to side.

The real cure for this is to make the head bracket a good fit in the gap and stop the column from flexing. However it would also make the head harder to move since it would be tighter in the middle and loose at the top and bottom.

I don't see any answer for this problem without a major redesign of the column and head hight adjustment mechanism.