Slitting Saw on small vertical mill - what size?

Hey everybody, just have another question in connection with my new (used) CH-10M vertical milling drilling machine (think Seig X2). The spindle on this thing is bored out for MT3 tooling and has a 12M-threaded drawbar.

I am sort of giving the nod to the tooling offered by the people at Arc Euro Trade. It would seem that I have the following choices.

If I mount a slitting saw arbor that is has direct fit MT3 taper shank on this mill then it looks like I have to use either 63mm diamter slitting saws (on a 16mm stub arbor) or else 80mm diameter slitting saws (on a 22mm stub arbor).

On the other hand, should I opt for stub arbors having the MT2 taper and then use a Morse Taper adaptor sleeve (MT3 to MT2) I can use slitting of either 50mm in diameter or else 63mm in diameter.

So now the questions:

A) What size of slitting saw can this thing can reasonably and safely swing? I know that the gearing on this little mill is a potential weak point (can shed transmission gear teeth when overstressed) and that no matter what slitting saw I choose I would have to advance the work slowly and carefully. But should I actually be afraid of mounting the larger diameter slitting saws?

B) Does the CH-10M mill actually even have enough 'oomph' to use the larger diameter slitting saws?

C) If I wanted to go for the smallest diameter slitting saws (50mm) I would need to use an adaptor sleeve (as well as cobble together an M10 drawbar). Is this a bad idea? Does the use of an adaptor sleeve necessarily mean I'm going to get more tool runout?

Any comments or advice richly appreciated.

I have completely given up trying to slit on my x2. It simply doesnt have enough torque. Instead I use the lathe in low and mount work in the tool post.

Hi Ignatz

I'm not familiar with the CH-10M - so I cannot help you in terms of this machines capabilities but I can tell you what I'd do (and have done)...

If you can mount an MT3 blank arbour in your lathe (?) - then I'd choose a slitting saw that was suitable for my immediate needs (how deep do you need to saw?) and then I'd make a saw arbour to match it. I'd then standardise on the bore of this saw in future. Saws of a particular bore will probably be available in several different diameters as well as a range of thickness.

For instance, all of my saws have a 1" bore and are mostly 3" diameter (I do have a couple of 4" and some 2" (ish) too). I have a few very thin blades as well as a set of blades in thicknesses from 1/32" to 1/8" (in 1/32" steps).

I've made saw holders (in MT1,2 &3) to suit my various machines and they are all for 1" bore saws (and this also co-incidentally happens to suit my horizontal milling machines too).

This seems to meet my own particular needs - which may be modest when to compared to others here.

Regards,

IanT

Here's my MT1 slitting saw ....the MT1 blank arbour had an extra mild steel 'collar' Loctited on to it and the new 'assembly' was then turned true and a 'cap' made to suit the saw's bore. The diameter of the arbour used affects the depth of cut you can make - so this is also a factor to consider when choosing a blade size...

Regards,

IanT

Surprised.. the only problem I've had on my X2 is narrow slitting saws wandering by anything over about 0.04" is fine.

Neil

Whichever you go for the 63mm length arbor with collars is more useful than the shorter MT3 for use with 16mm centre blades.

With slitting saws you also need to consider how much depth of cut you can obtain with various blade diameters and arbor collar diameters, max DOC will be: (blade diameter minus arbor collar diameter ) / 2

With some combinations this can be a very small max DOC.

I haven't any experience using the Sieg X2 but I'm sure with the correct set-up and choice of saw thickness, spindle speed and feedrate those machines are capable of the task. When slitting it is best to use a coolant sprayed onto the saw teeth when they leave the cut to remove any chips that may be between teeth, failing coolant an air blast will achieve the same but without the lubrication.

Because slitting is done at low speeds there may be a problem with available torque, fizzy mentions this problem.

Emgee

Thanks for the tips and advice up 'til now, guys.

Just postin' a picture of the CH-10M again to refresh your memory (should have done that to begin with)

The idea of using a slitting saw on the lathe would be just fine except... that my lathe is a Taig Micro Lathe. The Taig has served me well over the years, but the cost of equipping it to do milling work (milling attachment, mill vise, arbor and slitting saw) would be easily twice what I would spend to equip the vertical mill for slitting. And there just isn't a whole lot of XY milling/cutting range on that tiny lathe in the first place... which is why I purchased the vertical mill.

Does anyone have any advice regarding my comment about using the Morse Taper sleeve adaptor to use stub arbors with a smaller shank (MT2)? As I was wondering, does the use of an adaptor lead to excessive runout? It also seems to me that using one Morse Taper shank within another just has twice as many surfaces that could 'slip' while cutting. Does this tend to be a serious problem out there in the real world? On the other hand, given the fragile transmission gear tooth problem with this vertical mill (mentioned above), slipping surfaces could be regarded as a sort of 'safety clutch' (ha! ha!).

I've used MT adaptor sleeves in the past Ignast but mostly it's been to fit MT1 mounted accessories in my (MT2) Myford tailstock (for instance when using my smallest drill chuck or female centres). So any 'extra' run out present wasn't that apparent - as the taper was not rotating. I'm sure I've also used a MT3 > MT2 sleeve on the Victoria once in order to use a cutter (that didn't fit the MT3 tool holders I normally use) but it was a roughing job and to be honest I was more interested in shifting metal than anything else. Whilst I didn't notice a problem that I can recall, I don't think it would be an ideal example to give.

My gut feeling would be that any adaptor sleeve must introduce more run-out to some degree. It would of course depend on the quality of the sleeve - but there must be some additional inaccuracies introduced. If it was going to be a permanent 'mating' then it might be worth while testing the combined sleeve and taper - to see if a particular orientation of the native MT2 taper within the MT3 sleeve counteracted any run out inherent in each to some extent. If a position was found where the overall run out was minimised, then you could mark them accordingly and always set them up like that. Just a thought - I've not tried it myself I'm afraid.

With regards slippage - if you use a drawbar too tightly, I think you will find that your problem is less likely to be the taper slipping but more your ability to actually get the taper out of the machine after use. I believe it's why many prefer an R8 taper to a MT3 one on their mill.

Regards,

IanT

I have a Sieg X2, with a 3MT spindle. The slitting saws I have used successfully are the 80mm o/dia ones, ranging in thickness from 0.8mm up to 2mm thick. The arbor is an MT3 one, so it fits directly into the spindle

When cutting steel patience is a necessity. Cutting al. alloy is a piece of cake.

The major issue is the available depth of cut, which can cause some head scratching

Best of luck!!

cheers

Bill

If you get an MT3 1/2 in collet you can make a parallel shank arbor of choice. If you put a shoulder on it and tap for a 1/4in drawbar that passes through the collet thread (3/8 in) or metric equivalents then you won't have to worry about it moving up and down.

To answer the first question a clean new 2-3 adaptor should run true enough but the rusty one at the bottom of that box of bits at the boot sale best just for drills.

I am surprised that nobody has mentioned speed (of rotation - not feed). When I first got a mini mill, I also bought some slitting saws because I thought I might use them one day. Well, I did, and by running them at what I now know was far too high a speed, ended up with several rather expensive thin washers with slightly rippled and burnt edges. Slow and steady is best, although I haven't used them since as I've upgraded my mill and its lowest speed is 160rpm, probably slow enough for aluminium, but not, I suspect, for steel. What I need is a three phase motor and inverter - are you listening, Santa?

You can learn from my mistakes and save yourself a few shillings.

John

My X3 is happy at low speed with 100mm dia blades, I first cut several shallow passes to give a straight slot to stabilize the blade as it goes deeper. Easily slots the Harold Hall dividing head block. I use the MT3 16 and 22 arbor direct, well lubed with wd40 or such like. Take your time and traverse the table evenly.

Clive

I use a MT3 stub arbor from Arceurotrade on my admittedly larger mill. Most of my saws are about 3" with a 1" bore although I do have some smaller and larger ones. I used to use a small 1/2" shank arbor but it tended to self tighten in use making it difficult to change the blades. Unlike my new arbor which only takes 1" bore blades the small arbor could take different sizes from 1/2" - 1" so they do have their uses I guess.

From the armchair:

Isn't the issue with slitting saws the need for low spindle speeds? Some mills don't have enough torque at low spindle speeds and there is a side effect of slow running, in that there is not enough air being pulled through the motor to keep it cool. This is with reference to the smaller mills with electronic speed controls.

From the workshop:

I've also noticed with some belt driven mills, that the lowest speed ratio using a pulley size way off spec for the belt being used (ie the old Chester Eagle and similar clones). This means the belt slips.

Steve

This is a slitting saw arbor I made having experienced a wobbly Chinese one in the passed. It has been designed to fit in a 10mm collet so I could use it with my easychange tool holder on the Novamill. The mill has a 0.5hp motor and at low speeds and feeds it made a really nice job of slicing the bronze bearings in half for my Stuart 7A.

The saw in the arbor at the moment is 50mm diameter and I`m planning on a making another this weekend to fit the 63mm saw, both are about 0.5mm thick.

Nice job Michael. I too had a dose of the wobbly arbors. I cheated by using a blank end MT3 arbors from Arceurotrade, very little work work is needed to make them up. The MT2 sizes are really cost effective for this purpose - £3.78

Steve

If you use an MT2 arbor in a MT3 spindle then you can buy a sleeve with a threaded ring which allows you to extract the tool without banging the hell out of it. Arceuro have them I am sure.

Clive

I tell you its near impossible on my x2 - slow speed = very low torque. Might be better on later models with better motor but not on mine.

It all depends on how much you have s****d it fizzy ....For example, on the older X2s - brushed motor versions, we used to come across customers who had used fly cutters which had jammed for one reason or another many times, and the fault light came on suggesting to 're-consider' what you are doing. Still, some of these guys persisted in carrying on, resulting in more jams = fault lights. At some point, the control board may partly or fully give up the ghost. There is only so much that it (the board) or the motor can take. In turn, with regular faults over time, their machines somehow lost torque at the lower end due to possible fault developing on the control board?...This also used to happen if they 'tweaked' the component the wrong way or too much (dont know correct name/dont know correct direction) on the control board, or if the said component setting wasn't right or had moved/changed. If you look at the board on this page about two thirds of the way down, I believe that it is one of the three blue pots which can be set by using a + screw driver. They are usually covered by some kind of wax. You can adjust them, but not recommended, as if you get it wrong, one adjustment can effect another, as extremely minute adjustments are required.

Ketan at ARC

Ignast,
I would advise against using any plain MT2 MT3 adaptor because you would lose the drawbar locking of the arbor carrying the slitting cutter and side thrust is such that your slitter and arbor would sooner or later walk out of the adaptor (with obvious disastrous results).
I'm not aquainted with Clive's releasing ring but this may help but only if it provides that positive hold of the whole cutter assembly into the spindle.
Depending on your detail requirements it sounds like an MT3 blank end adaptor machined to suit would be your best bet

Bob D