Up grade milling machine

Hello all, I have SX2p mill with R3, it's been a good machine and is still in great order. I'm thinking of a upgrade to the X3 or any other suggestions, the SX2p just needs to be a bit more power and rigid. The other day doing a short cut with a 12m end mill I climbed mill after a cut and the machine didn't like it, and I damaged the job I was doing. Its mistakes like this I don't need and perhaps the X3 would of taken it. Looking at the price of machines in my opinion are still cheap,I just got a garage door in GRP fitted and compared to a X3 and what's involved in producing it they're a bargain.

Thanks Bob

Hi Bob,

A friend of mine has the Sieg SX3 and likes it, he has had no troubles. I have a 10 year old milling machine similar to the Amadeal VM25 (but with a brushed mtor), no troubles and I like the long table.

Thor

I had a SX2P and used it for five years building a 3 1/2” 9F rolling chassis among other things, felt that was about its limit. Wanted a heavier more powerful machine to go to 5” Super Simplex, both machined from solid, no castings. After looking I went for a Warco GH Universal, been very pleased with it, fitted dro myself. The difference is what you would expect with much more power and strokes, the additional weight makes a big difference. I will probably add some power feed in the future, particularly on Z. Of course prices have risen in the last couple of years and will continue so don’t delay your choice and purchase, it is Christmas.

I think you will have a job finding an X3 certainly new are not available that I know of. So it's going to be an SX3 or SX3.5 if you want to go up in the Sieg range.

Climb milling requires an effective backlash eliminator or a ball screw with stepper or servo control. I take very light climb cuts and put the axis locks on to provide some additional drag but not lock the axis, a fine balancing act but it seems to work. Backlash is the enemy of climb milling and even a new mill will have some and it will increase with wear. Some mills have a crude slit nut that can be adjusted to pinch the thread but as most screws wear unevenly adjustment will be impossible to be satisfactory in all positions, big boys mills can have hydraulic elimination but this is found on serious professional equipment.

Mike

Having owned a similar machine to the Warco HOWARDT has I can confirm that machines of that style are seriously capable. In practice moving to a Bridgeport hasn't given me significantly more metal removal capability. The win was much more space to play with and far better visibility under the head. Peering round that large box casting when trying to do a small job close in to the vice reduced me to serious profanity on more than one occasion. Which was one reason why it had to go.

The aforementioned mill had a two speed belt drive from a VFD controlled motor. The speed ranges were very similar to those on the Seig SX3.5, albeit about 1/4 slower in high range and going down to 70 rpm at the bottom, proving incredibly well chosen in use. I don't recall ever needing to change ranges mid job. The ample overlap basically made jobs either high speed or low speed ones.

In my view either the Warco or the Seig SX3.5 would be about as capable a machine as you can cram into a typical home shop. (Mine shared half an 8 x 12 shed with a SouthBend Heavy 10 lathe, a compressor and the common 6x4 bandsaw. Think thin being important when machining.) Above that you are into ex-industrial capability where the limitation is more "how fast do I want to cover the floor with chips".

But do get one with a motor on the Z lift axis. The handles provided are always too short and the position too much of a reach making shifting a total pain. The other reason mine went out of the door.

Clive

Rigid is not an attribute that comes to the top of my mind when describing the SX3.5. I don't have any experience of anything similar to compare though. I have had a few mistakes and damaged the job... including a simple 'cut a 1.8 mm deep 10mm wide slot in a myford cross slide... Milling cutters can get pulled down in the collet if you don't tighten them enough. Maybe the noises and vibration are a good thing though... like an alarm bell.. but that would still mean you have to pay some attention and remove headphones and not turn your back while the power feed engaged.

It is powerful - plenty enough to get you in trouble. I appreciate the emergency stop button. The powefeed has an over current protection but is powerful enough before it gets there. It isn't operated by the emergency stop (I guess lots of 'add on' power feeds are similar) ... it really should be for me and a is mod I am considering over Christmas!

I can imagine some people are reading the above paragraphs in combination and cringing.

Climb milling is particularly challenging in Y (across the bed). 

I am not convinced about the long bed - the SX3 'safe' operating volume would be much smaller in practice. I'm sure I will be convinced once I start milling crossbow prods. At the moment the large table is just a place to store a dividing head... which I have also discovered is a bad practice when you got a power feed... as is leaving the vice spanner on while machining.

Power up and down is great.. but coarse.

DRO a MUST for me. Allows a bodger to do rmore accurate work within the attention span.

The crate is large and awkward to move. Too big for one man to install unless you got clever leavers - like an engine hoist - in which case it easy. But once in place, the mill is quite small. I have it on wheels and have moved it a lot. This is the main reason I didn't go for a knee mill or old iron. Wish I had rigidity, but I very much appreciate the mobility.

Edited By jaCK Hobson on 10/12/2022 11:49:25

I don't own an SX3.5, but a Warco WM18, which has a similar table size, I think.

I'm curious to know why you're experiencing pull down of the milling cutter. I've never had that whether I've been using direct collets, an end-mill holder, or an ER collet chuck.

Which of these are you using, and what installation procedure are you following when loading cutters? If you're using one of the first or third in my list when you get pull down, what size shank is the cutter and what size the collet?

10mm R8 collet not tight enough - probably only hand tight after I got distracted while looking for spanner thing. Try doing yours up hand-tight and see what happens in a large chunk of cast iron at high feedrate. Mine started out as .5mm finishing cut but was more like 5 mm when i hit the stop button.

Ah, right, so simple operator error then. I assumed, jaCK, from your general air of disappointment with the SX3.5 that you were attributing the pull-down of milling cutters to some fault with the machine, particularly when your opening words called its rigidity into question.

I'm still puzzled how you can logically criticize a machine for a lack of rigidity [or stiffness] when the problem as you've explained it is that you didn't do something up tightly enough. It's a bit like accusing a tap of leaking when you simply haven't turned the tap far enough down for the washer to properly seat.

I think you are taking my observations in a strange direction. I think I made more than one. They don't have to be related.

Like Bill I've not had problems of cutters pulling out of any of the three Sieg mills I run.

Although I don't have a SX3.5 it should certainly be capable of a 10mm wide x 1.8mm deep cut without excess vibration. Your tactic of 0.5mm deep passes is not ideal as it is just going to wear the corners off the cutter which will then cause vibration as it will then be blunt.

This is the less substantial SX2.7 taking a 10 x 1.8mm cut in steel and then iron and it was not vibrating across the workbemch, just a slight movement of the £1 coins. Also worth noting that I had the rotary table and chuck on the mill at the time so the head is almost at the top of the column which if you are going to see a lack of rigidity will be in this situation. Healthy looking chips in both materials and minimal burrs so cutter is cutting, full details in video description.

Edited By JasonB on 10/12/2022 16:31:33

Sure the SX3.5 can take cuts deeper than .5mm. But I wouldn't call it rigid. For comparison, I wouldn't call my Super 7 rigid. On that 2.7 example cut, how much material would be taken off if you went back over the same cut without further adjusting the depth? I feel that if I am chasing a few hundredths of mm dimension then the spring in the machine has to be accounted for?

You can mess up work on any mill if you operate it incorrectly or outside its parameters - I gave an example at the risk of my reputation. No need to rub it in.

I do not feel I am overly critical of the SX3.5 here. I think the forum should not discourage observations from owners to help people understand what they will have to feel comfortable with in order to be happy with their purchase. If I had read an opinion like this before buying then I might have had a more realistic expectation and be more satisfied with my purchase (and read that sentence again if you think I'm saying I'm dissatisfied). I guessed it probably wasn't going to be as rigid as as a VMC, or tom senior or centec - which weigh a lot more - so I am not generally disappointed - just specifically disappointed, and only slightly. But that is because I didn't know what to expect - there is little info.

I am guessing though. I would be interested to have rigidity figures from different mills. From pictures, the column on the the SX3.5 can look a lot more massive than it is - a lot of the depth is steel cladding containing the electrics. Jason has said many times that 'best practice' needs adjusting for these types of mills - the solution might be lighter but faster cuts.

I don't even 'know' what the Sx3.5 'should' be reasonably capable of. Tell me and I will run some tests if I have the metal and cutters.

I like the overall size and power of the SX3.5 - it fits my workshop and methods. I did have cause to wonder recently... Black Friday 20% discount at Axminster suddenly made their version of the SX3 with DRO an attractive alternative if you don't need the table length.

I would not expect anything to come off depth wise on the return cut. However with the 3-flute cutter in the video I would expect it to be pulled slightly sideways during the cut and then take a small amount off one side on the return, this is why usual advice is to use a 2-flute "slot drill" for slots where width matters if only taking a single pass width wise.

I've done another video showing the 3-flute and what that took off on the return and then the same 1.8 x 10 cut with a 2-flute which hardly removes anything.

As Mentioned I'm right at the top of the column so using a vice so the head is lower would reduce this more as would doing away with the ER 25 collet holder and holding with an R8 collet which reduces spindle overhang by about 60mm.

Was this a demonstration Jason or do you often use end mills instead of slot drills on slots.?

🙄 regards Martin

Ah reading the whole post I see it was

I don't think Bill was taking your comment in a strange direction, he was just reading what you wrote.

Martin, I often suggest a 3-flute as a good all rounder and that is what I tend to use most of the time. If the width was critical I would either have used a 2-flute or more likely an 8mm down the middle and then a pass down each side to bring the cut to width.

Bill has not said what he was using so could have been 2, 3 or 4-flute so the 3-flute was a good middle of the road choice for the demo.

To avoid further puzzlement, I am not implying my comment about rigidity is related to me not doing up a collet tight enough. It surprised me that people should infer such. It is obvious I'm not relating it to the fact that the power feed is not operated by the emergency stop etc? Am I negatively criticizing the SX3.5 for being less rigid that it should be? I didn't mean to. I meant to imply it is not the most rigid machine and I add the qualification that I don't know what to expect.

The side pull is an issue I have also encountered; particularly in Y; my observation is that it very much seems to be related to depth of cut. One might expect it to be inversely related to how rigid the system is and proportional to load/chipload/depth of cut). If this has been encountered on an SX2 then one still might encounter it on an SX3.5.

Jack, how many flutes to your cutter?

I would say there is not a lot of difference between the rigidity of one make of hobby bench top mill to another of similar size. None will be as rigid as old industrial iron or big and heavy new iron but they are a different class of machine.

The same comments about using 2-flute cutters for slots to reduce side cutting due to flex have always been true and you will find it in books going back years so not just a problem found on hobby machines though due to their lighter construction they will suffer from it more than a 5T industrial machine would..

As it is the cutting force that deflects the tool then reducing that by taking shallower cuts will indeed reduce the tendency for deflection if you are using a single full cutter width pass. As will minimal tool stickout, minimal quill extension, locking all unused axis, etc.