[bhdavis1cnc]

I'm considering replacing my old 3.75kw Perske spindle on my 4x8 cnc router with a 4kw spindle. However my Delta VFD is rated at 3.75kw.

Is that extra .25kw oversize on the new spindle going to be a problem for the existing Delta VFD? I'd of course prefer to stay with the Delta both for a cost savings and because it is already fully integrated into the system.

This is a light duty router and is unlikely to ever push the spindle to it's 4kw power capacity.

Thanks,
BH

[joeavaerage]

Hi,
that will work fine. If there is a shortcoming is that if and when the spindle is demanded of overload torque the VFD will not be able to deliver as much current for as
long as you might like. As you say it may well never come to pass.

I have just recently bought a new spindle, still waiting for it to clears Customs. It is 3.5kW rated but 6kW peak. At peak it draws 21A (at 400VAC). That might suggest an 11kW VFD, being rated
at 25A, but this seems excessive. A 7.5kW VFD is rated at 17A and a 5.5kW spindle is rated at 14A. In truth all would work, and I suspect I'd be happy with any of them, but I think the 7.5kW
version is probably the best compromise for me. My spindle requires 1333Hz to reach its max of 40,000rpm, and so I need a Delta MS model, the high-speed HA model. They are not cheap!

Craig

[bhdavis1cnc]

Thank you for the advice.

40,000 rpm !?!? What are you cutting with it?

BH

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[joeavaerage]

Hi,
I use my machine to make PCB's. In fact its the main thing I do with it, and I rely on its output for my business.

For many years I have used an 800W 24000 rpm spindle, and its been perfect. It does not do well at slow speeds, in particular its very poor in steel.
I have been of a mind to replace my little spindle for a while. I don't actually need more power, nor more speed, 24000rpm has been good enough for ten years,
so would be good enough for another ten. What I did want is ATC. The manual change is a bit of a drag.

I saw this spindle on EBay. It's 3.5kW and 3.34Nm at 10,000rpm (continuously rated) and 40,000rpm max. The increase in power and especially at lower rpm means that this spindle can be used
for cutting steel. Its not perfect for steel mind, buts its about ten-fold better than what I have. That it can go to 40,000rpm is a bonus if drilling tiny holes, which I do sometimes,
but I doubt I'll use it a great deal, high-speed causes the bearings to wear out much faster, The extra steel capacity is welcome but its really the HSK32 ATC tool interface that sold me.
The Vietnamese seller has been pretty generous and thrown in 10 HSK32 to ER20 tool holders and the price includes shipping to New Zealand.

Craig

[bhdavis1cnc]

This is what's behind my spindle change.

https://rapidchangeatc.com/

I'm retired so my router is purely for my enjoyment and some fun money from things I make on it. I sold my business in 2016 and my 5x10 router with ATC went with it. My retirement machine has been a slow upgrade project and ATC is the last step. Hard to justify the costs and complexity of a true ATC system though which is why I got excited when I found the above low tech rack. I've been communicating with the fellow who came up with it and as soon as he adds a ER25 capability I'll get one.

BH

[joeavaerage]

Hi,
have you used shrink fit tooling?

I like the security and concentricity of shrink fit. I understand that they can be used and reused for many years....so that appeals as well.

What I don't know is whether there is a through hole? Especially with a 1/8th shank tool if you have a bad 'whoopsie' you could easily end up breaking it flush
with the toolholder. The question is 'can you heat the toolholder and puh the broken tool stub out?' I imagine that you could, but I have yet to find anyone
who can say 'yes, so and so brand do that'.

All of my PCB making tools are 1/8th shank, and there are very few manufacturers of HSK32 with 1/8th bore shrink fit toolholders. RegoFix make them, but over $1000NZD each!!!
Man the Swiss sure know how to charge!! There are some much cheaper but still goog brands in 6mm, 8mm and 10mm bore. I found this US barnd:

https://www.ebay.com/itm/35467539373...Bk9SR46UluCZYw

Craig