High speed spindle

I would like to add a high speed spindle to my PCNC770 but can't justify a Tormach speeder. I want to use mostly very small (1.0-0.5mm or smaller) cutters in aluminum, brass and Delrin so minimal runout is important.

What are people's experiences with the Kress 800 that Tormach sells? Other than slightly more power and 220 volt operation, is the Kress 1050 significantly better? Any users of Suhner units? Is there any other spindle that I should consider? Are there any accurate but reasonably priced spindles using brushless motors?

I have a hard time believing any of those small die grinders will give you both low runout and long life in a CNC application. For about the same money, I'd rather take a chance on one of the Chinese spindle+VFD packages.

Regards,
Ray L.

Check out Wolfgang Engineering spindles.

Agreed but... I've read reports of wretched runout on some of the Chinese spindles. Some YouTube videos show claim that the Kress is wonderful (see: HF Spindel vs. Kress - Rundlauf - YouTube ) plus Tormach sells it so it is probably pretty good.

Well, if you look at that video, it's not that bad. When he measures on the tool, the Kress looks like nearly zero runout, while the Chinese one shows about 0.005mm/0.0002", which is actually pretty darned good for the money. Then, when he tests the taper on the Chinese one, it's basically zero, which says it was his collet creating the runout, not the spindle itself. A better collet should solve the problem. You can also probably rotate the collet and tool to reduce the runout if necessary.

Regards,
Ray L.

It's always a bit dangerous relying on a one-off Youtube video demo for what you should expect if you purchase a similar item. If run-out is that important to you then ask the supplier/manufacturer to supply details of the specified maximum run-out. If he can't or wont then don't buy it.

Regards
Phil:)

I couldn't find a datasheet in English on the Kress site. Based on the translated datasheet on the Tormach site ( http://www.tormach.com/uploads/168/t...ation-pdf.html ) I believe that the axial runout was 0.01mm, 0.02mm radial runout at the collet and 0.05mm 40mm from the collet. This is considerably worse than the results in the YouTube video. My understanding is that the Tormach document is for a test of a single unit so it isn't exactly definitive either! Which is why I hoped to get experiences from actual users.

The CNC woodworking community is very interested in this topic. Take a look over at precisebits.com for some useful supplies (for example, calibration rods and precision collets) as well as some thoughts about low cost and surprisingly high precision spindles (also known as "routers"). Some pretty good tutorials, too.

I picked up a tormach Kress unit and used it for the 1st time last week. Runout on the taper was 0.0003". On a tool in the 1/8" collet, it was about 0.0008". Much worse than I had hoped for. That being said, I did some 29k rpm machining with a 1/32" em and had great success. I was only cutting on 2 of the 4 teeth I'm sure.

Noise is ok. Speed control is quite good, checked it with a tach.

I have several Kress 800-FME spindles, and have worn most of them out! They are excellent CNC engraving spindles!

Measuring the run out at the spindle's internal collet taper is more accurate than measuring the run out of a tool clamped in a low quality collet. There are several grades of collets available, and not all have the best TIR (Total Indicator Reading), while most are poorly made and have sloppy concentricity! You must read the fine print when buying spring collets!

When checking a spindle taper I think it is not just the taper run-out that is of interest. The precision of the angle of the taper is also critical. Too large or too small an angle will mean that even a good collet will not necessarily pull-up squarely when the retaining nut is tightened.

Regards
Phil:)

PS: I think it is relatively easy to build a spindle with the taper running true - you grind the taper after the spindle is assembled, with the spindle running in its own bearings. However getting the necessary taper angle precision is a completely different ball game.

Quote:

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Originally Posted by philbur

It's always a bit dangerous relying on a one-off Youtube video demo for what you should expect if you purchase a similar item. If run-out is that important to you then ask the supplier/manufacturer to supply details of the specified maximum run-out. If he can't or wont then don't buy it.

Regards
Phil:)

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That is so correct.

I have a series II and do a lot of 3d machining. There are pulleys out there that with a little modification will fit the 1100 and while you'll loose some torque you'll gain spindle speed. I am sure the same is true for the 700. I started down this path and stopped by a buddy. He showed up with a higher rpm motor with more HP but it was too big. And then my ADD kicked in.

So you know your job best... what kind of spindle speeds are you looking for?

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