Machine Accessories

[Roger BensonParticipant @rogerbenson45349]

I am now the proud owner of an SX2.7 mill. Now it is time to accessorize.

I have decided on the ARC rotary table but I am having a problem in deciding between the 4" or 6". I also want an Independent 4 jaw chuck for the SC4 lathe. Now comes the problem I would like to be able to use the same chuck on both machines if possible, be it 4" or 6". The 6" rotary table comes with an 125mm chuck backplate. Firstly is a 6" rotary table suitable for the SX2.7? Is a 125mm chuck suitable for an SC4 lathe? I understand that I may have to fabricate a back plate to fit a 125mm chuck to the SC4?

[Roger BensonParticipant @rogerbenson45349]

Deciding on what size tooling

[John HaineParticipant @johnhaine32865]

I have 2 rotary tables and have hardly ever used either. Do you really need one? Maybe wait until you get a job that can only be tackled with a rotary table?

Based on my recent experience, having fitted a DRO to my mill I wonder why I went for so long without. If your mill doesn't already have a DRO then it is perhaps a much more useful upgrade and a good one allows you to do things like set out accurate hole circles that would otherwise need a rotary table.

While the Arc website suggests the 6" rotary table for the 2.7, it strikes me as a bit big, the base being 176 x 178 mm while the table is only 100 or 125 mm wide depending on the model, so the RT will overhang the table.

One thing I have found is that a 4 jaw chuck can be very useful on the mill for holding smaller work needing to be constrained vertically around 2 horizontal axes. Arc suggest 100mm 4J chucks for the SC4 for which the smaller RT would be fine if you do buy one, and it would fit the mill table.

Have you looked at other makes? The Arc RTs are very nice but expensive if it doesn't get much use.

[Thor 🇳🇴Participant @thor]

Ho Roger,

Congratulations with your new milling machine. would agree with John that a 6 in. RT might be on the large side. The 6 in. RT is taller than the 4 in. so you loose a bit of room with the 6 in. RT.
I use a homemade 5 in. RT on my milling machine that is roughly the same size as your SX 2.7. Do you have a specific job where you need a RT? I assume you already have a good machine vise and clamping system, that was my first accessories for my milling machine.

Thor

[not done it yetParticipant @notdoneityet]

I have two 150mm RTs. One is likely good enough for most, I suppose, but occasionally I want one on each mill (or don’t want to take down one already set up).

Depends on how you might want to use it. Laying flat might restrict the working height in some scenarios and on end (vertical), they often need to be well away from the cutter if they interfere with long travel.

A small one is handy if it remains within the table size but might not give as much support to anything of maximum diameter that could be accepted. One of mine had the tailstock with it – often very handy to have if using the table in the vertical position.

Get the 4 jaw chuck first – unless you have a need for a rotary table, is my advice. I bought both my RTs second hand, so at the right price.🙂 If the second had been smaller, it would likely have been better (for my smaller mill), but I took what was on offer….

[Roger BensonParticipant @rogerbenson45349]

Yes good points. I don't have any accessories yet. A machine vice and clamp set are in my basket. I agree about the DRO that is being decided now. I would only need 2 axis as the Z is on the SX2.7. A DRO is definitely on the list but again which one?

[Peter G. ShawParticipant @peterg-shaw75338]

I don't have a rotary table, nor do I have an SC4 lathe. However, my lathe, 105mm centre height, came with a 100mm 3-jaw chuck and a 160mm 4 jaw chuck. The major problem I have with the 4 jaw is that the centre hole, at about 40mm diameter makes it difficult to hold smaller items. As a result I have separately bought an 80mm 4 jaw chuck. Both chucks get about equal usage depending on the size of the work.

Peter G. Shaw

[Roger BensonParticipant @rogerbenson45349]

As far as the DRO goes, this is top of the list so far is the Universal DRO Package.

2 Axis M-DRO Mill Function Magnetic Encoder Digital Readout Package

[JasonBModerator @jasonb]

Well I've been happily using ARCs 6" and my old Soba 6 on the SX2.7 as well as my slightly larger X3, both get used quite a bit though maybe not quite as often for curved work now that I have CNC (as I think John does)

Not had problems of head room when using them vertically (work axis horizontal) but can get a little tight when laid flat on it's back with 5" 3 jaw and backplate but it has not stopped me doing what I wanted with it.

Standard length table is actually 140mm wide not 100 as stated above which refers to width between the slots.

A few images of it in action

I don't think much of the above could have been done with a DRO and not a rotary table

As you may be able to gather it's the more used of the two now as I find the 72:1 ratio more useful for the numbers I seem to want to index, there is a reason spin indexers have 36 divisions! Also being able to set the round scale to zero allows you to set the work in whatever orientation you want and have a straight side lined up with zero.

You can also see that it does not need an item to be that large before clamping room can become an issue, I've not touched my 4" table since I got the first 6" one.

Edited By JasonB on 15/05/2020 13:10:41

[not done it yetParticipant @notdoneityet]

DRO? Go for a full 3 axis if funds allow (not separate items for each axis). They are transferrable between machines.

Likely not needed initially, but when you wish to drill holes on a pitch circle or mill a curve, the full kit offers options that are clearly not available with some simpler versions. I will never use all the facilities on mine, but the ones I do use makes life much easier.

The one you are looking at would be OK. But do you need such long scales, just to cut away large chunks?

Cheaper separate axis items may only indicate to 2 significant figures and be accurate to less than that – but, again, it depends on your future use. This may be applicable to your current z axis?

You may only be thinking of avoiding backlash issues initially (usually the first use) or easily converting between imperial to metric but they are so much more useful than that!

I have separate encoders/readouts on lathe and one mill and the full kit on the other mill. Wish, now, I had a full dro on the other mill.

[BazyleParticipant @bazyle]

Golly gosh that 6 in table is a price!. have a look at lesser makes, like this on the Chronos site but also look at RDG and a few others. The one I linked gets you dividing capability too so saves you the cost of a dividing head. there is probably someone on here that has a Soba to tell you the spacing of the mounting holes.

Something to consider is a smaller chuck mounted on a short morse taper that you can transfer from the lathe to the table and have it right on centre.

[John HaineParticipant @johnhaine32865]

I just fitted an M-DRO 3-axis system with mag scales and it's excellent.

[Martin ConnellyParticipant @martinconnelly55370]

I have a 100mm chuck mounted on a piece of plate that I clamp to the mill when I want to hold round items easily. For larger items I just clamp a larger chuck directly to the mill. I agree with the posts above, with CNC a rotary table is redundant, a DRO designed to suit a a mill makes circular arrays of holes a simple job and wait until you need a RT before buying one. There are often work arounds for machining curves without a RT.

Martin C

[Clive FosterParticipant @clivefoster55965]

Purchase of a proper DRO system having effective PCD and other functions has to come before investing in a rotary table unless you have some very rotary table specific needs.

Most good DRO systems also have a curve generating function using multiple small X & Y feeds. Redefines the concept of mind numbing as you are basically doing CNC the manual way but it gets the job done. I have to admit that the couple or three times I've done a curve that way the time taken wasn't vastly different to what would have been needed when using a rotary table given the time needed to swop the vice for the table. Curves were something around 1/3rd of a circle I think. One of the times when just sucking up and getting on with the job beats trying to be clever, one day I might learn.

I'm inclined to think that, if you have the vertical space, a spindexer would be a better earlier investment (after the vice, DRO and table clamp kit) than a conventional horizontal – vertical rotary table. Certainly mine comes out about 6 times as often as one of the rotary tables. I have a 5C chuck for mine which is the usual work holding device despite having full sets of 5c collets in both metric and imperial.

These days ER makes more sense for the collets.

Its a pity there appears to be no kit or published design to convert a spindexer to a GHT style dividing head as such would seem well suited to ME work at an appropriate cost. The worm drive for continuous rotation being possibly of more immediate value than pure dividing head capabilities. Accessory plates for Vertex et al rotary tables would seem the sensible way to add full dividing capabilities. Perhaps Ketan at Arc could put a package together.

When considering the size of a rotary table its important not to underestimate the space taken up by clamps. As Jasons middle picture shows conventionla clamping usually needs more space allocated than the work. Especially with small tables. I personally think that conventional T slots with bar and step block clamping systems become somewhat inappropriate below 8" diameter due to the space needed. Can maybe used on a 6", as Jason shows, but on 4" frankly fergeddit.

A grid of tapped holes plate gives more, and more complex, clamping options than slots although the clamps are usually weaker. Which probably matters not for small work and correspondingly small cuts. Jasons first picture shows a clamp arrangment much more typical of those used with grid of holes than with Tee slots. One easily overlooked advantage of the grid of holes plate is that cantilever clamp carriers can be arranged when really short of area in one direction.

Clive

Edited By Clive Foster on 15/05/2020 13:30:46

Edited By Clive Foster on 15/05/2020 13:32:27

[Henry BrownParticipant @henrybrown95529]

Probably the most useful and cost effective tools for the mill is one of these Roger!

[not done it yetParticipant @notdoneityet]

Posted by Henry Brown on 17/05/2020 20:57:46:

Probably the most useful and cost effective tools for the mill is one of these Roger!

And exactly how much did that useful little tool cost you? Looks really expensive.🙂 Mine don’t even have a wooden handle (although it may make finding them easier).🙂

The OP might even consider a set-up (like doubleboost’s?) to make them – or just order one from him?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Henry Brown on 17/05/2020 20:57:46:

Probably the most useful and cost effective tools for the mill is one of these Roger!

[…]

.

Nicely done, Henry

… That makes my old toothbrush look rather shabby

MichaelG.

[AdrianRParticipant @adrianr18614]

Sigh, Now tooth brushes are so last year I have another job on the todo list.

I have spent a while working with an old mill and making do with a drill vice, home made clamps and angle plates, I would say get a good vice. I also found I wanted to hold things at angles. So I have bought an angled work table and digital angle gauge.

I had to decide between rotary table and DRO, I chose 3 axis DRO. What finally persuaded me to get a DRO was after using a £4 plastic digital vernier as an improvised X DRO. Even if I had not bought a new mill I would have got a DRO for the old mill.

Adrian

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