Planning on buying a Sherline mill (ball lead screw or ACME thread type)
Hi,
After much deliberation I have decided to buy a CNC mill for some small aluminum parts manufacturing. Our parts are not more than 200 MM wide, the stocks we use are normally 6 to 10 MM thick stock aluminum, usually sheets or bus bars.
Initially I thought of the Shapeoko Pro 5 CNC router, this has very good CAD ->CAM->G code support. This is one of the main features that has encouraged me to look into the ready to use desktop machines. However I am worried about the rigidity of the machine when milling aluminum/brass parts, besides this is primarily a CNC router for woodworking, although it can also be used for metal milling.
The Sherline approach is very attractive to me as there is lot flexibility in choosing the stepper motors, Gcode senders, GRBL based cards etc. For the sherline model I am considering the 12" Deluxe table top mill with ball lead screws (https://www.sherline.com/product/685...s/#description) or also the 14 " Bench top 8 direction mill (https://www.sherline.com/product/200...tion-mill-pkg/)
My question is
1. Is the ball type lead screw better or the ACME thread one?
2. We will not be doing full fledged production ( just small scale production, 5-10 parts per month). But we do need the machine for R&D purposes so the 8 direction mill is a better option. However I am worried about backlash in the ACME threads, so the ball type maybe a better option in terms of longevity, which do you think is better?
3. I am planning to go for 3 axis stepper motors, with step drivers connected to a WiXHC (Mach4 USB CNC controller) (https://www.wixhc.cn/product/mach4-c...er-card-mk4-m4).
Here the design approach would be CAD (Onshape for Fusion)-> CAM (fusion or something similar)->G Code sender->USB CNC controller unit
is this possible with the Sherline CNC mill.
4. Is the collet size suitable for most metal milling work, in both machines? Most CNC router uses ER-11 collet, for the Sherline CNC millI was told the feed rate would be slow, is this correct?
FYI We do have the Sherline Lathe, the machine build is pretty solid, however we do have problems sourcing the special tool bits, other than that no other issues.
thanks
a
Re: Planning on buying a Sherline mill (ball lead screw or ACME thread type)
HI,
I suspect that either of those machines are just not rigid enough to do aluminum on a regular basis. Both will cut aluminum but as slow as 'paint drying'
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1. Is the ball type lead screw better or the ACME thread one?
Ballscrew, hands down. There will always be lash with an ACME screw and it will ruin your CNC experience.
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so the ball type maybe a better option in terms of longevity, which do you think is better?
Its going to take a bloody long time to wear either of them out. If your business model is good you'll have upgraded to the 'real deal' long before you wear them out.
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connected to a WiXHC (Mach4 USB CNC controller)
ABSOLUTELY NOT......STAY AWAY FROM XHC!!! The XHC Mach4 plugin is completely flawed and XHC do NOTHING about it. It does not even support Mach's editable GUI, you are constrained to use .wxMach,
avoid like the plague!!. I use an Ethernet SmmothStepper, my own design breakout board and Mach4 and have done so for eight years, it works well......but AVOID XHC.
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4. Is the collet size suitable for most metal milling work, in both machines? Most CNC router uses ER-11 collet, for the Sherline CNC millI was told the feed rate would be slow, is this correct?
The problem with Sherline is that the spindle is so small that it lacks the torque to run larger tools. Collets that can hold 1/8th shanked tools and another collet for 1/4 inch are useful as is a 6mm collet and even sometimes
a 4mm collet. Most of my tools that I use in my small (800W 24000 rpm) spindle have 1/8 shank. My second spindle (1.8kW, 6.2Nm cont, at 3500rpm) has an ER25 tool holder and can take up to 16mm tools,
I use it for steel and stainless where you need high torque not high speed.
To be honest I don't think the Sherline is going to do it for you. I think you should take a look at some of the drill-mills out there. They are rigid enough to do a good job in aluminum and with care a good job in steel too.
You'd want to convert to CNC, but there are plenty of threads about converting such machines. A well sorted conversion of one of these machines would last you many years whereas you would tire of the limitations
of a Sherline or a CNC router. This is an example....one of many of the same general sort.
https://rongfu.com/mill-drill-machin...-machine-rf45/
Craig
Re: Planning on buying a Sherline mill (ball lead screw or ACME thread type)
Thanks for the tips.
Some issues about the Sherline worry me. First is the spindle cannot be controlled via software, this defeats the purpose of an automated CNC setup. I am hoping the software would take care of some of the aspects of CNC machining like spindle control. The other issue is the non standard collet. I see most CNC routers/mills use the ER-11 collet type, I am not sure I can get support for the type of collet supported by Sherline. This was an issue we faced with the Sherline lathe, we could not get the tool bits suitable for the lathe anywhere here in India.
I feel the Sherline mill systems are more suited for a DIY environment.
The issue with the CNC routers is the high spindle speeds, tool breakage is a big concern for me as is the somewhat narrow margin of error these machines operate on. Regarding rigidity of the machine, I think they can be reinforced with stiffer struts & wasteboards.
The idea of converting a drill mill is quite good, i would love to go that way, if only I had the time. We do have a similar manual mill that could do with a conversion, however we could never get around to it...!!!
Re: Planning on buying a Sherline mill (ball lead screw or ACME thread type)
Hi,
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Regarding rigidity of the machine, I think they can be reinforced with stiffer struts & wasteboards.
BS, rigidity is in the DNA of the machine, its either got a certain level of rigidity or not, there is no adding it after the fact.
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First is the spindle cannot be controlled via software, this defeats the purpose of an automated CNC setup
Does it really matter, 99% of the time you turn the spindle on to full speed and it stays there. If you had many different materials and a toolchanger with many different tools
then speed control becomes important. For most hobbyists though it's power on/ power off and no in between.
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The other issue is the non standard collet. I see most CNC routers/mills use the ER-11 collet type,
Then replace the spindle with a VFD driven spindle with ER collets if thats your desire. A VFD will help with speed control. Note however all the 24000 rpm asynchronous spindles out there
CAN be speed controlled but it's BAD NEWS to run them at part speeds, they tend to overheat. So just because you have speed control does not necessarily mean that its a good idea to use it.
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The idea of converting a drill mill is quite good, i would love to go that way, if only I had the time.
Research Tormach, Syil and Hass Mini-Mill.
Craig
