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 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.

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 6×4 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

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?

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.

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

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.

Ah reading the whole post I see it was

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.

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.

Yer, I had bought one cutter – 3 flute as I read in someone's book that it was a good all rounder

So many time people discuss rigidity of machines and spindles but strangely no one attempts to measure this significant attribute in order to make the discussions more objective. Its not hard to do. I have done it on my own Wabeco mill and the result is shown below. All I did was put a short stub in the collet with a DI earthed to the base. I then pulled the stub with a spring balance in the direction I wanted to measure the rigidity, then plotted a graph. You can see there is a considerable difference depending on the direction of pull.

The reason I did this was that I planned some simple improvements to the machine and wanted to make sure I was getting a quantifiable return on my investment. Unfortunately, with so many interesting things to do, this work is still in progress. One day I will report the conclusion but I can tell already that some re-machining of parts of the machine has improved my ability to work with tougher materials.

But as has been said in this thread, high rigitity is not crucial if one is prepared to compromise on the time it takes to do a task. Its more of a 'nice to have'. It would be good though if suppliers made some attempt to quantify rigidity of their products to help in comparing machines at purchase time, instead of us relying on folklore and hearsay.

Gerry