Zenford Zeigler Retrofit

Personally, for a wood router I like about a 2.2-5kw spindle, if you are going to want to use 1/2" shank tools. (A lot more, if you want to use really big form shaped tools or do heavy milling.) If you don't plan on using anything bigger than a 1/4" diameter tool shank then the smaller 1-1.5kw ones should be ok. I've had good luck with the few super inexpensive, cheap Chinese spindles we've bought off ebay so far. (and they cost about 1/3 the price of the German or Italian spindles we used to buy.)

I can't however comment on the quality of the Chinese VFDs that are often sold with these spindles. I haven't had a chance to test one, and I'm a bit scared of this type of Chinese electronics. (I'm told the quality can be very hit or miss.)

Mine is an Italian spindle made by Elte, paired with an LS VFD. I didn't buy it on ebay, I just called a company specialising in such products and talked with an engineer. He matched both products to my application and when I received the stuff, the VFD was already programmed to match the spindle. All I had to do was make a mounting bracket.

Sorry, my experience might not be that helpful to you because I'm not much of a technical expert. I needed the spindle for work and was prepared to pay the ca. 750€ to have a plug and play solution. I've had no problems whatsoever with this combo or with connecting the VFD to the spindle. I've been using it for several months now (5 maybe?).

If you don't have plans for the machine to amortize the cost of the spindle for now and would rather get it as cheaply as possible my suggestion would be to peruse some cutting formulas and tool catalogues. That way you can come up with an optimum fit on your own and then browse for reviews from buyers to choose the gear that matches your specs.

What I mean is that tool catalogues list the recommended cutting speed (Vc) for each bit and material. That way you can calculate how much rpm you will really need from the formula: rpm=(Vc*1000)/(3,14*D), where D is the tool diameter. The catalogue will also list maximum cutting depth and width (ap and ae, respectively), while the feed is derived from the formula: Vf=fz*z*rpm (fz is feed per tooth and z is the number of teeth).

Then you can take all that data and use the following formula to determine how much power you will need (in kW): Pc=(ae*ap*Vf*kc)/(60*10^6) (this is for metric units; kc stands for specific cutting force in N/mm2 that you can get for various materials either online or from a tool catalogue). I know this sounds like a PITA but you can easily calculate how much speed and power you will need for various operations and it will demistify your choice, giving you more confidence when you order.

This might be an okay substitute for transferring the responsibility to a guy/company that get paid to sell you their stuff, especially if you're not in a hurry. I apologize if you know these formulas already. I learned them during a CNC course I took before buying my machine, but the best reference online IMO is the Sandvik knowledge base, available through www.sandvik.coromant.com/en-gb/knowledge....aspx?Country=plthis link . There you will also find formulas for imperial units, which are a bit different.

You'll find that the cutting forces for small end mills in light materials are pathetically low and your primary driving factor for the choice might be speed. Depending on how fast your CNC can go, you may find you want a slower or a faster spindle. Sorry for the long post!

Wow, Thanks for the info. I have been using the router for about 12 months now and have the tooling and cutting data pretty sorted. Don't "need" a spindle motor really, but it would be nice to have. Especially a nice, well made one like you have.

I'm pretty familiar with tooling catalogs and cutting formulas, Been a machinist for nearly 25 years, But we never stop learning. I really enjoy learning from everyone here, and i'm always humbled by the amount of people willing to give you their time to help out. Great people.

I'm sure people will learn alot from what you have written above. Its great information that covers the fundamentals of machining. Totally agree with the Sandvik knowledge base. A few years ago i got to go to Sandvik in Melbourne, for milling fundamentals training (through work). Was nice to get a refresher on the theory and we got to see some of their new tooling in action, running on machines i can only dream of running. Thank you very much for posting.

Cheers

Matt

Any progress to your mill?
I have to be honest and say that I am looking at getting on the mill retrofit bandwagon again and was searching for all things Zenford Ziegler and came upon your thread.
Did you have any more luck with the servo drives? I have a mate that does the occasional machine retrofit as part of his business and he did a mill with brushed DC servos, and took the encoders straight to LinuxCNC and closed loop to the controller. He was extremely impressed with the results and claims it is one of the best retrofits he has ever done.
Myself I am currently getting PCB's built for a DsPIC based drive, if it works I'll most likely use that for my mill, time will tell, I am no electronics guru, just tinkering really.

Russell.

If anyone is interested, I have two Zenford Ziegler mills to dispose of from a deceased estate, both with turrets. One was from Defence at Lithgow, and I don’t know where the other was sourced. One was in regular use. Also bucket loads of manuals, and some bt 40 tooling. Price will be very cheap. They are located near Romsey, VIC on a farm. Also available is a cnc Hardinge from Defence, that was in regular use. (5 years ago was when he passed away)
A crane truck would be needed. For more info, feel free to contact me.
Cheers, Peter

Thanks for the heads up Peter, while I cannot possibly fit anything more in my shed and the missus has a thing against large machinery/motorbikes in the lounge room (women are strange at times), I will pass this onto anyone I know that may have more shed space/more understanding missus.

Cheers.
Russell.

Thanks Peter, Would be interested to see what you have there. Not sure the best way to contact you directly?
I have not been able to really do much with my Zenford in quite a long time. I started a little machine shop, and dont get much time to play with the retrofit anymore. Would love to get back to it though. Might be a bit like yours Russell... a super long project, haha