Promica X3 CNC Mill for Sale

[swarfmeister]

For a few bob more I'd be tempted to replace the MT3 spindle with the R8 spindle.

If you want to buy the machine you could no doubt improve it, that's what I did and I learned a lot building and using it. Or better still buy a new KX3S for $15k, top of the line Tormach, or any of the machines on Grays Online that require an entire two car garage, forklift to move it, three phase power and a trained technician to repair it when it breaks down. This one works properly, but with some scope to modify along the way to suit its new owner's needs and tastes at a significant discount over new.

The simple way to speed up the spindles is just to turn the supplied belt drive backwards and then it will go to around 4K RPM which is just fine in a garage for a hobbiest who wants to cut aluminum a lot of the time. This one has been converted to a high quality US made motor controller as the Chinese ones are junk and fail. That conversion is a lot more difficult on a SX3 - not to mention they are less rigid. I also have a second belt and pulleys to replace the noisy gears on the spindle, which is another common mod and gets the spindle to 6K RPM or so. I don't see the point to crashing a carbide end mill into steel on a 300kg machine, but I may be in the minority there I guess.

Anyway, I am looking for someone who knows what they are buying. A few people have taken the time to contact me, ask for a few photos and arrange to see the machine. This suits me as I can tell people more about the machine in 5-10 minutes on the phone or in person than I can on an Internet forum. Suggestions from people to sell on eBay, that the MT3 spindle is no good for milling, needs a drawbar, needs an enclosure, doesn't compare with a $20k+ machine etc really just aren't particularly helpful.

[handlewanker]

That is true, you can improve anything to your likes etc.

I have to ask you seriously just for the record.......if this was an ongoing project wouldn't you prefer to have the R8 spindle.....it opens up a whole world of possibilities.......I don't know if it's possible to just swap over the innards to get to R8.

I don't think "crashing the carbide into steel" is an actual happening......the wear factor for fast feed rates and higher speed is one thing you want.......I doubt that a hogging mode would be indulged with........CNC is all about many light cuts which for a manual application would drive you to drink.

Many light cuts and a fast feed rate maximises the ability of the machine to resist deflection due to a relatively light build.

Anyway, best of luck with the sale....hope you get your price.
Ian.

[daniellyall]

Ian you can go as fast and as deep as you wont on a CNC machine they are not made for light cuts unless its a cheap as lump of crud and you have to.

[handlewanker]

LOL.....tain't so Dan, you have to work within the machine characteristics..........I cut shallow, almost full cutter diam and a feed that doesn't make vibration and/0r deflection........speed is fairly high but HSS has it's ;limits for rpm....carbide works better.

This is opposite to the deep and small set over where you are prone to cutter deflection

The last cut is actually what determines how the work turns out.

If you push the envelope too far the work piece suffers and you get vague dimension and possibly missed steps......all machine are not all that good to go for broke just because you think it's OK to do so or want to.....just my opinion.

Don't forget, a machine like the SX3 or X3 has a loose head to column fit in the dovetails because it is being used as a Z axis......the looseness leads to head nod due to cutter forces pushing against the dovetails.......only retrofitting the column with linear rails will cure that syndrome.

As a matter of interest, the X3 in question does not appear (I couldn't see one in the photo) to have any head weight compensation like a gas strut.....whatever......that is one area that SHOULD have been a priority for any CNC retrofit where the head is now doing the Z axis move..
Ian.

[daniellyall]

realy

[swarfmeister]

I personally wouldn't convert to an R8 as I already have MT3 tools and they fit into the tailstock of my lathe. There is just no return on the costs of a power drawbar or ATC for me so its not a consideration. There is a mob in the UK that would sell a whole new quil in R8 if you wanted it. It might even be esiaer than that. The parts guides are all there too if someone gets keen to do the research.

When I purchased the kit originally I asked about gas struts. Marc told me he had tested it and the finish qualty was reduced, which makes perfect sense if you consider the cutter is now floating rather than having the weight of the head holding the tool down in the cut. His view was that gas struts are only required if you have underpowered steppers without correct gearing etc. Now he could have been winding me up but given he had a number of these machines producing the kit parts I think he would have installed some struts on his own machines if it was necessary. Its true the Z axis is a little slower at 1000 mm/min, which I don't see as an issue because very little of the average job requires Z moves. 1000 mm/min is still is still pretty fast compared to most conversions I have seen on here, 500 mm seems more typical. If you have a light head and linear rail perhaps its a different situation.

[handlewanker]

Hi, R8 with a 19mm collet can give you access to cheaper 19mm plain shank tooling that would give you a TTS type tool change and a power draw bar........a power draw bar is much more convenient to clamp and unclamp a tool than a nut on the end of a plain draw bar........that does not translate to an auto tool changer as that is streets ahead on any mill.

I would not think having to screw in and unscrew a drawbar and knock out a MT3 shank is something to write home about even for a low production run......I did that for a few years on my Bridgeport..

A gas strut does take a lot of weight off the Z stepper motor as there's a lot of iron in the head, no matter how it's seen the less the better...........I see in the photo that the quill handle is still in position......all of that is unnecessary weight to lift......just my opinion.
Ian.

[swarfmeister]

No question an R8 is convenient to change tools with a power drawbar. I'd sure like a Lambo to replace my daily drive as well.

The purpose of the counterbalance is to reduce the force required to move the head in the upward direction (increased speed) and/or to stop the head running backwards when the power is turned off. Neither are an issue for me and a gas strut will not result in a better quality finish - possibly the reverse. The mill often gets used in semi-manual mode - something a CNC only mill is not capable of, so the quill handles are installed unless I am running jobs where they might get in the way. Frankly they weigh nothing in the scheme of things.

Your insistence that these things are absolutely essential leaves me wondering if you have read too much vendor marketing material.

[phomann]

Swarfmeister,
If a potential purchaser asks about TTS tooling, Tormach sells a MT3 3/4” collet to suit their tool holders.

Cheers,

Peter


Sent from my iPhone using Tapatalk

[handlewanker]

No question an R8 is convenient to change tools with a power drawbar. I'd sure like a Lambo to replace my daily drive as well.

The purpose of the counterbalance is to reduce the force required to move the head in the upward direction (increased speed) and/or to stop the head running backwards when the power is turned off. Neither are an issue for me and a gas strut will not result in a better quality finish - possibly the reverse. The mill often gets used in semi-manual mode - something a CNC only mill is not capable of, so the quill handles are installed unless I am running jobs where they might get in the way. Frankly they weigh nothing in the scheme of things.

Your insistence that these things are absolutely essential leaves me wondering if you have read too much vendor marketing material.

Not really.......vendor blurbs are usually weighted in their favour for marketing.....they sell the sizzle more than the sausage as that's what the marketing responds to.

I just mentioned a few points I would consider necessary to go the CNC route.....one reason I waited 2 years and spent almost 10 grand to get the machine I wanted.

Of course it will work just as you have it.........but I think it can work better given a few other retrofits......you only really want to tear a machine apart once to get there and never again once it up and running.
Ian.

[handlewanker]

Swarfmeister,
If a potential purchaser asks about TTS tooling, Tormach sells a MT3 3/4” collet to suit their tool holders.

Cheers,

Peter


Sent from my iPhone using Tapatalk

Peter........I'm surprised you even think that could be an option.

MT3 is bad enough with having to bang out a MT3 shanked tool but add a collet with the same aspect and the extra cost for TTS tooling and you're walking backwards......just my opinion.
Ian.

[daniellyall]

https://www.tormach.com/store/index....show&ref=30251

[handlewanker]

The fact that Tormach supply a 3/4" collet for MT3 adaptation to expand their range to utilize their products doesn't mean it's automatically good.

From bitter experience of MT3 on a Brridgeport mill I can categorically say that it's a crap system, only fit for a drilling machine......just my opinion based upon actual experience.

Anyway, the thread is drifting once again into hypothesis of peripherals and has no bearing on the salability of the said X# mill on GUMTREE......a buyer will no doubt take the options into consideration.....I'm only expressing a point of view as I see it.
Ian.

[RCaffin]

I am slightly confused (a normal state). I found it very hard to imagine Tormach using an MT3 fitting on their mills, so I looked up the specs.
440: R8
770: R8
1100: R8 (option of BT30)

Where does the MT3 come into all this?

Cheers
Roger
PS: MT3 is fine for drilling, but I would never ever use it for milling.

[handlewanker]

Hi Rog.....allow me to most humbly allay your confusion...........Tormach just have this beast in their arsenal for those people who have MT3 spindles and it is my opinion that they have one to ensure that sales of their TTS tooling possibly might happen.
Ian.

[RCaffin]

Ka-ching!
Understood.
Thanks
Cheers
Roger