Which to buy?

[John HaineParticipant @johnhaine32865]

Jason, the OP asked what tooth counts and materials I was using. If you profile the gears out of flat plate or on the end of a bar the limits are the usable width of the table (max diameter) and minimum usable size of cutter (minimum modulus). Bigger teeth aren't a problem even for a light mill since the cut width is (say) 1mm and depth 0.25mm even cutting a large tooth. Only feasible with CNC, Christopher is already using CNC on a router and apparently making gears this way.

[Christopher ChurchillParticipant @christopherchurchill11285]

My problem here is I don't have a way to drive somewhere to pick up a machine I need to have this delivered and I'm not fiding any second hand mill's in my area or that will ship to me

so I'm kind of limited to purchasing it new.

Posted by Martin Connelly on 19/11/2021 13:11:26:

If you look at used mills and a round column vertical mill is available do not dismiss it out of hand. The ability to rotate the head around the column allows the spindle to be further away from the table centreline for larger diameter gears.

For example if you had a Ø70 cutter and a Ø100 gear blank you need at least 85mm between the spindle centre line and the dividing head centre line. With a square column mill this may be hard to achieve without having the rotary table hanging over the edge of the table.

Martin C

[Christopher ChurchillParticipant @christopherchurchill11285]

I'm again not sure what I'm seeing here, excuse the ignorance.

Posted by John Haine on 19/11/2021 13:49:22:

Jason, the OP asked what tooth counts and materials I was using. If you profile the gears out of flat plate or on the end of a bar the limits are the usable width of the table (max diameter) and minimum usable size of cutter (minimum modulus). Bigger teeth aren't a problem even for a light mill since the cut width is (say) 1mm and depth 0.25mm even cutting a large tooth. Only feasible with CNC, Christopher is already using CNC on a router and apparently making gears this way.

[EmgeeParticipant @emgee]

Christopher

The cut gear resting on the nose of the collet chuck, a piece of paper below it would have helped you identify it.

Emgee

[JasonBModerator @jasonb]

Sorry John, could not see anywhere wherte the OP asked what size gears you were cutting, I know he has a CNC router I suggested he use that if not metal before you tried to suggest he buy one

 

As to what is in John's picture this is similar to a gear being held on an arbout in turn held by an ER collet

Edited By JasonB on 19/11/2021 16:24:52

[JasonBModerator @jasonb]

Some pleasant surprises on the SX2.7 mill, but first

This is a 1MOD cutter mounted on a R8 shank milling arbour. One advantage with these is the overall diameter is smaller than a similar tooth size imperial cutter at 50mm vs 63mm so you gain a bit of room using metric.

Now the usual way most set up a rotary table and tailstock is to have the cutter behind the work and as I said this is going to limit the diameter of gear you can cut. here the gear is 78mm dia and you would be hard pushed to get much larger without hanging the rotary table off the mill's table.

This is as far forward as the table will go

But then I remembered a conversation with Ketan at ARC about how far back some of teh Sieg mills tables will go so thought I would try it that way round. The protective bellows on the column are just retained at the bottom by magnets so can be slid up out the way to gain a bit more room too.

I think you could probably manage 170mm dia gear blanks set up like this and still have the rotary table and tailstock lined up with the middle tee slot.

If doing a gear of this size on the SX2.7 I think I would not use a single central arbour but instead bolt the blank to the rotary table with some suitable length spacers in a similar way to Andrew's photo as it will be a lot more rigid and no risk of the blank rotating on the arbour

The SX2P being a bit smaller may manage 140-150mm dia and with moderate tooth size should cut the mustard. but would be worth checking the available table travel.

[Christopher ChurchillParticipant @christopherchurchill11285]

THIS IS ABSOLUTELY AMAZING!!

I'm going to go for the Sieg 2.7 then! this will quit me just fine for now!!! Thank you SO SO SO much for this setup.

Now just to decide from where I should be buying this from…

Posted by JasonB on 19/11/2021 18:35:04:

Some pleasant surprises on the SX2.7 mill, but first

This is a 1MOD cutter mounted on a R8 shank milling arbour. One advantage with these is the overall diameter is smaller than a similar tooth size imperial cutter at 50mm vs 63mm so you gain a bit of room using metric.

Now the usual way most set up a rotary table and tailstock is to have the cutter behind the work and as I said this is going to limit the diameter of gear you can cut. here the gear is 78mm dia and you would be hard pushed to get much larger without hanging the rotary table off the mill's table.

This is as far forward as the table will go

But then I remembered a conversation with Ketan at ARC about how far back some of teh Sieg mills tables will go so thought I would try it that way round. The protective bellows on the column are just retained at the bottom by magnets so can be slid up out the way to gain a bit more room too.

I think you could probably manage 170mm dia gear blanks set up like this and still have the rotary table and tailstock lined up with the middle tee slot.

If doing a gear of this size on the SX2.7 I think I would not use a single central arbour but instead bolt the blank to the rotary table with some suitable length spacers in a similar way to Andrew's photo as it will be a lot more rigid and no risk of the blank rotating on the arbour

The SX2P being a bit smaller may manage 140-150mm dia and with moderate tooth size should cut the mustard. but would be worth checking the available table travel.

[Howard LewisParticipant @howardlewis46836]

In answer to the question re measuring equipment, this is my method, used so far for 20DP, 1.25 Mod and 1.5 Module gears.

You will need your Digital Calliper, and / or at least one Micrometer,; and a DTI and magnetic base.

You are not actually cutting the gear teeth, but the gaps between them, so that the teeth are what is left after you have finished cutting!

Mount a small 3 jaw or a 4 jaw independent chuck with a 2 MT shank into the lathe (Sleeves need to bring upto the MT in the lathe spindle ) 2 MT because my Rotary table has a 2 MT bore. Yours may be different.

If the gear is to be cut on an existing shaft, use the 4 jaw, and clock the workpiece or mandrel to bring it central,

Bear in mind that if using a 3 jaw, turning the blank to size will bring the OD central about about the axis, irrespective of any eccentricity of the raw material, but the shaft for the needs to be turned to size at the same time to ensure concentricity between shaft and gear.

Ensure that the blank is long enough for the gear cutter to clear both the chuck jaws and the Tailstock!

Turn the blank to size, and centre drill the end of the mandrel.

.Without disturbing the work in the chuck,move the whole assembly to the Rotary Table, supporting the outer end .

measure the thickness of the cutter.Using the "oily fag paper" method bring the side of the cutter into contact with the top of the blank, and Zero the Z axis dial

Withdraw the cutter in the Y axis (This assumes that the cut will ,be applied along the X axis. )

Lower the cutter by half the thickness of the cutter plus half the diameter on the blank. The centerline of the cutter should now be on the centreline of the blank.

Again using the "oily fag paper"method touch the cutter against the blank, and set the Y axis dial to Zero.

Assuming that the cutter is behind the blank, move the cutter into position on the X axis, so that it clear of the gear blank, and ready to cut.

Using the Y axis dial, move the table to apply the depth of cut (Probably marked on the cutter, or can be found in, or calculated from, Ivan Law's book ), and lock it.

Lock the Rotary Table, and take out any backlash, before engaging the spring loaded pin on the handle in a hole min the hole in th required ring of holes, and set the Fingers against the pin and to the required number of holes

Setting the fingers allow you to increment by the required number of hole, without having to count each time..

(The chart with the Rotary Table should give the number of turns and holes on a particular hole ring on the Division plate for the number of divisions that you require. )

Check that the figure are correct.

I found the hard way that the chart for my R T contained errors and omissions, and wasted a week repeatedly making scrap, waiting for Loctite to cure,and losing confidence in my ability to count, before making up a spreadsheet which revealed the errors!

So, if your RT has a 90:1 ratio, and you wished to cut a 13T gear, having cut the cut the first gash, the table would need to be unlocked and incremented by 6 turns and 36 holes on a 39 hole circle, before being relocked, between cuts.

Remember the backlash, so always increment in the same direction, and reposition the fingers!Having set the machine speed to the closest to give the required cutting speed, apply whatever is your choice of lubricant to the blank.

Start the machine and very gently feed the cutter into the blank until it is clear of the other side.

Stop the machine, and return the X axis to the starting point.

Unlock the RT and increment for the next gash, and relock.

Take the next cut.

Repeat the above, until you have the required gear.

If the increment is incorrect, the gear teeth will be too thick or too thin except for the last tooth!

HTH

Howard

[DiogenesIIParticipant @diogenesii]

Just 'cos no-one else has raised the point, are there specific issues with the lathe that mean things aren't very satisfactory?

..if you are going to be using it to make blanks, arbors to mount them on, etc., the I guess this might be as good a place as any to address any shortcomings?

[Nigel McBurney 1Participant @nigelmcburney1]

I would prefer a dividing head any day,with its positive indexing,

[Christopher ChurchillParticipant @christopherchurchill11285]

Nothing in particular is wrong with it I just want a bigger one with a bit more rigidity

Posted by DiogenesII on 20/11/2021 09:53:15:

Just 'cos no-one else has raised the point, are there specific issues with the lathe that mean things aren't very satisfactory?

..if you are going to be using it to make blanks, arbors to mount them on, etc., the I guess this might be as good a place as any to address any shortcomings?

[JasonBModerator @jasonb]

Posted by Nigel McBurney 1 on 20/11/2021 10:02:32:

I would prefer a dividing head any day,with its positive indexing,

Is that any different to a rotary table with dividing plate? I did not bother to fit that as it would not have affected the measurements.

R/T also has the advantage on large dia gear like the OP wants to cut of providing a bigger surface to bolt the gear too and less overhang than a chuck and arbor

Pic of the R/T complete with indexing plates, quadrant, etc

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Christopher Churchill on 20/11/2021 10:09:25:

Nothing in particular is wrong with it I just want a bigger one with a bit more rigidity

Posted by DiogenesII on 20/11/2021 09:53:15:

Just 'cos no-one else has raised the point, are there specific issues with the lathe that mean things aren't very satisfactory?

[…]

.

Hence my [evidently mis-judged] suggestion that you modify the lathe to make a useful tool.
Wheel-cutting engine / Dividing Head / whatever … Make of it what you will.

MichaelG.

[Christopher ChurchillParticipant @christopherchurchill11285]

My confidence level just isn't there yet to pull apart the mini lathe and make something else out of it… I don't think I'm good enough to get the kind of tolerance levels needed to make something use full out of it…

I DO have in mind potentially converting it into a small cnc mini lathe and running small woodworking projects through it, but I have 0 idea where to start…

Posted by Michael Gilligan on 20/11/2021 10:41:30:

Posted by Christopher Churchill on 20/11/2021 10:09:25:

Nothing in particular is wrong with it I just want a bigger one with a bit more rigidity

Posted by DiogenesII on 20/11/2021 09:53:15:

Just 'cos no-one else has raised the point, are there specific issues with the lathe that mean things aren't very satisfactory?

[…]

.

Hence my [evidently mis-judged] suggestion that you modify the lathe to make a useful tool.
Wheel-cutting engine / Dividing Head / whatever … Make of it what you will.

MichaelG.

[Christopher ChurchillParticipant @christopherchurchill11285]

thank you for the detailed post @howard, I think I have a decent understanding now after much reading the last couple of days about this and the help here!

ref this:

You will need your Digital Calliper, and / or at least one Micrometer,; and a DTI and magnetic base.

do you have any recommendations on which of these items to purchase? at the moment I think I'm going in on a 2.7 Sieg from https://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/Milling-Machines/SIEG-SX27-Mill/SIEG-SX27-HiTorque-Mill I assume they have these measuring tools I need do you recommend them?

Chris

[SillyOldDufferModerator @sillyoldduffer]

Posted by Christopher Churchill on 19/11/2021 14:29:53:

My problem here is I don't have a way to drive somewhere to pick up a machine I need to have this delivered and I'm not fiding any second hand mill's in my area or that will ship to me

so I'm kind of limited to purchasing it new…

 

Practical constraints often limit what can be done.

Some lucky folk have plenty of space and live in areas full of second-hand machines and helpful scrapyards giving away machinable metal. Not me! I am fortunate to live in an English village that everyone delivers too. And when it arrives, equipment goes straight up a short tarmac drive into my garage workshop, easy. My experience is different to anyone living up a lane in the Scottish Highlands, were couriers are unwilling to go.

Unfortunately, I only have a single garage which limits the size of my machines, as does the available power. I had to be careful what I bought, and I chose to solve all the problems by buying new. I had a budget, several suppliers with web catalogues, and all I had to do was choose one, tick boxes, and authorise payment. I don't have a family full of burly he-men to help, so I bought an engine crane. The machine weights I bought can be handled with a crane and one assistant, son not available, so daughter helped.

Experience with a mini-lathe confirmed the oft repeated advice about lathes and milling machines: bigger is better! It's because small work can be done on big machines, but small machines can't do big work. Less obviously, working close to a machine's maximum capacity means the operator spends ages thinking hard about set-ups, and endlessly sorting out awkward work-holding problems. Frustrating when they disappear if only a few more inches were available. The exception to the 'bigger is better' rule is anyone specialising on small stuff such as clock making.

The window and house door in my single garage decided where the bench went, The position of the bench defined the floor space available for the mill, lathe and band-saw. (Note the band-saw is the single most useful tool in my workshop because it eliminates hours of tedious exhausting hack sawing and it saws straighter than I do. You will soon want one!)

There was just enough space with maximum headroom adjacent to my bench to take the mill. In my workshop headroom is limited by the ceiling and lights and the space taken by the up and over door. There isn't enough headroom for the type of milling machine with a knee, and floor space for these bigger machines is tight too. However, a Warco WM18 fitted neatly: this is the largest mill of the small pattern, ie with tilting column and fixed height table. (Similar available from other suppliers.) Not the best mill in the world but 1100W and plenty of room on the machine for what I do. How tall you are is issue with the WM18 size because short people have to stretch to reach the top column handle. OK for me at 5' 11". I think a WM18 could just accommodate a 200mm diameter gear wheel without me doing anything clever, but 150mm is more reasonable. The limits are table traverse; diameter and height of the rotary table that the machine can carry; and the up-down head movement.

Positioning the mill defined the space I had available for a lathe and I bought a WM280 to fit in it. I could have squeezed slightly larger in, but it's best to leave working space for humans too, plus the band-saw, tool-cabinet and crane. The lathe is positioned to allow long work pieces to pass through the headstock and give easy access to the change gears. Blocking access to the headstock by positioning the lathe in a corner is a common mistake.

My particular layout discouraged me putting the machines against a wall, perhaps a good thing. Against the wall is a good way of maximising space but a right pain when rear access is needed for maintenance.

It's apparent my approach to outfitting a workshop didn't focus on brand-names, 'quality', country of origin, or features. All I need is general purpose machines. Instead, I valued being able to choose size and weight to fit the available space; off-the-shelf availability; delivery arranged by the supplier, not me; and consumer protection. If a machine turned out to be a lemon, it can be returned. Returnin a heavy machine is a mild pain in the UK, and I don't know if the same protections are available to a purchaser in Eire now we have border complications. I suggest a chat with suppliers is in order. May not be a problem: Warco say they deliver anywhere in the world, but I've no idea what the Terms and Conditions are.

There's a post somewhere on the forum where an Irish buyer hired a van and collected a second machine from the Midlands. More trouble and risk than I would be prepared to take, but it worked out OK for him.

Dave

 

 

Edited By SillyOldDuffer on 20/11/2021 12:40:18

[JasonBModerator @jasonb]

You should be able to makle a saving on postage if you order any additional items at the same time as they will put them in the crate that the mill comes in which is a set pallet rate delivery, you can squeeze a lot into those crates

I did but my DTI from ARC, something like this will do for most jobs mounted on this mag base

[Ketan SwaliParticipant @ketanswali79440]

Posted by Christopher Churchill on 19/11/2021 19:11:36:

THIS IS ABSOLUTELY AMAZING!!

I'm going to go for the Sieg 2.7 then! this will quit me just fine for now!!! Thank you SO SO SO much for this setup.

If doing a gear of this size on the SX2.7 I think I would not use a single central arbour but instead bolt the blank to the rotary table with some suitable length spacers in a similar way to Andrew's photo as it will be a lot more rigid and no risk of the blank rotating on the arbour

Hello Christropher,

Before you get too carried away, I would strongly suggest you buy and read link: Milling for Beginners written by Jason Ballamy. It is written in plain English. It is based on the SX2.7 mill. It addresses issues on how to use small mills in general, as well as helps you understand limitations.

With regards to rigidity, Andrew is fortunate to have a good old second hand industrial machine, with horizontal attachment to cut gear teeth easily in one pass. To put it into context, the machine on which he is cutting the gear probably weighs around four times or more than an SX2.7 vertical mill. As Andrew stated, gear cutting on vertical mill can be problematic. Even if you tried to bolt the blank onto the rotary table in a similar way to Andrews suggestion, it would be wrong to think that this is the only rigidity issue, and that you will get the same results as Andrew, because to start with the physical weight of the SX2.7 is much lighter than Andrews.

Andrews approach is correct for the type of machine he has. For the SX2.7, Jasons approach is correct, but it is combined with knowledge/experience of how to use a small light weight small mill. You also need to consider what material you are cutting, along with speed, feed and depth of cut more appropriate to any machine you ultimately decide to buy. How things happen on one machine will be different from how they will work on another model of a machine.

Ketan at ARC

[Christopher ChurchillParticipant @christopherchurchill11285]

Thank you for taking the time Ketan ( I understand you run Arc right? ), and not trying to just get a sale it means a lot…

I've added that book to my cart on Arc and will pick it up at the same time, in all honesty at this point I'm just waiting to see if there are any Black friday deals.

I do think that the sieg 2.7 is for me though I kind of understand the basics of weight and rigidity whilst I'm posting now and asking questions this purchase of a mill has been on my wishlist for about 1.5 years now and I think I'm ready to take the plunge finally!

thanks again

Chris

Posted by Ketan Swali on 20/11/2021 13:52:21:

Posted by Christopher Churchill on 19/11/2021 19:11:36:

THIS IS ABSOLUTELY AMAZING!!

I'm going to go for the Sieg 2.7 then! this will quit me just fine for now!!! Thank you SO SO SO much for this setup.

If doing a gear of this size on the SX2.7 I think I would not use a single central arbour but instead bolt the blank to the rotary table with some suitable length spacers in a similar way to Andrew's photo as it will be a lot more rigid and no risk of the blank rotating on the arbour

Hello Christropher,

Before you get too carried away, I would strongly suggest you buy and read link: Milling for Beginners written by Jason Ballamy. It is written in plain English. It is based on the SX2.7 mill. It addresses issues on how to use small mills in general, as well as helps you understand limitations.

With regards to rigidity, Andrew is fortunate to have a good old second hand industrial machine, with horizontal attachment to cut gear teeth easily in one pass. To put it into context, the machine on which he is cutting the gear probably weighs around four times or more than an SX2.7 vertical mill. As Andrew stated, gear cutting on vertical mill can be problematic. Even if you tried to bolt the blank onto the rotary table in a similar way to Andrews suggestion, it would be wrong to think that this is the only rigidity issue, and that you will get the same results as Andrew, because to start with the physical weight of the SX2.7 is much lighter than Andrews.

Andrews approach is correct for the type of machine he has. For the SX2.7, Jasons approach is correct, but it is combined with knowledge/experience of how to use a small light weight small mill. You also need to consider what material you are cutting, along with speed, feed and depth of cut more appropriate to any machine you ultimately decide to buy. How things happen on one machine will be different from how they will work on another model of a machine.

Ketan at ARC

[Anonymous]

Some of the notes made by Ketan are a bit wide of the mark.

It is correct that the machine shown is ex-industrial, but it is a universal horizontal mill so does not have, or need, a horizontal attachment. Conversely I do have a horizontal attachment for my vertical mill:

But I wouldn't normally use it for gear cutting as it is a bit wobbly.

The horizontal mill shown has travels not that different from a SX2.7, 500mm in X and 200mm in Y, but it weighs about 15 times as much. I used the rotary table to cut the gear shown as the gear blank was too large to fit under arbor and cutter.

Andrew

[Ketan SwaliParticipant @ketanswali79440]

Posted by Andrew Johnston on 20/11/2021 15:50:06:

Some of the notes made by Ketan are a bit wide of the mark.

The horizontal mill shown has travels not that different from a SX2.7, 500mm in X and 200mm in Y, but it weighs about 15 times as much. I used the rotary table to cut the gear shown as the gear blank was too large to fit under arbor and cutter.

Andrew

[Ketan SwaliParticipant @ketanswali79440]

Posted by Christopher Churchill on 20/11/2021 13:59:36:

Thank you for taking the time Ketan ( I understand you run Arc right? ), and not trying to just get a sale it means a lot…

I've added that book to my cart on Arc and will pick it up at the same time, in all honesty at this point I'm just waiting to see if there are any Black friday deals.

Hi Chris

I own Arc, but nowadays I just work part time on some back office projects, and I look in on forum threads and comment now and then.

Our Ian along with Brett and the team run the business. I have no idea if there will be any Black Friday deals, and if so, what they are likely to be. If you want to discuss your mill requirement for shipment to Ireland, I would suggest you call and speak with Ian.

Ketan at ARC

[Martin ConnellyParticipant @martinconnelly55370]

This is the last gear I made. It was a piece of 10mm scrap plate and I drilled the 4 holes in it to put it over the jaws of a 4 jaw chuck to hold it for turning the outside diameter and to bore the centre without disturbing it. A bit over Ø150mm. It was mounted on a home made arbor to rotate it for cutting the gaps (not the teeth as pointed out earlier) so I mounted some step blocks on the mill table to take the reaction pressure from the cutter to avoid ringing and unwanted movement.

The one below it is an OEM gear that I was matching.

My milling setup was similar to what Jason shows but was on the far side of the table. I think I did 4 passes and a couple of spring passes for each position.

Martin C

[JasonBModerator @jasonb]

Well having said the SX2.7 could do it I thought I had better make sure or risk not being in Chris's good books.

Not wanting to waste a whole 6" circle of steel I just radiused the end of a piece of flat bar to use for the test. I thought O would use the ARC rotary table and 151T was a size that came up on the chart and about the middle of Chris's size requirement, the actual blank diameter being 153mm for 1MOD size teeth.

As I said earlier at this sort of diameter a single central arbor is asking for trouble so a proper gear would be best drilled 4 times like in Martin's photo and then bolted to the rotary table with some spacers so the cutter can run out and not cut the table. So the flat bar was bolted down with some 15-30-60 blocks as spacers.

I also made sure the R/T was fixed well with 4 clamps. On of the odd things with the ARC rotary tables is they mount on the right hand side of the table which did give me some issues of the quill spider handle hitting the R/T so I had more quill extended out of the head than I would have liked. Also at this cutting diameter the milling arbor fouled the dividing plate so I had to resort to handwheel divisions. I expect most will opt for a left hand mounting R/T which won't have the quill problems.

As I've said before the small vari speed mills are best run on the fast side for the cutter so I went with 260rpm. Full depth cut ( 2.25mm) so just one pass per tooth gap. The cheap cutter has seen better days and does not run particularly true and having to feed one handed while filming did not help but it cut an acceptable "gear" which could be done better once div plates set up and feeding with two hands.

I think this diameter and tooth size is about as big as the SX2.7 can be expected to handle without putting undue loads on it.

And meshed with a commercial gear

Not the best video but will give an idea of it cutting.

[Howard LewisParticipant @howardlewis46836]

When you buy your Rotary Table, (A Horizontal / Vertical type hopefully ) do get the Tailstock with it, as well as the Division Plates..

In my case the Division Plates were bought after the R T (A Vertex HV6 now about 20 years old ) and last of all came a Tailstock.

With 20 / 20 hindsight, and more experience, buying everything at the same time would have been far better.

This eventually brought me to aligning the R T and the Tailstock. (The methods used were contained in an article in M E W, some time ago. ) It was time well spent, ensuring that the RT was aligned to the Tailstock and the Mill table, whilst the RT aligned the Tailstock with the centre at the correct height..

The Tailstock will support the arbor on which the gear blank is mounted, and will improve the rigidity which is ESSENTIAL in any machining or measuring operation.

Gashing the blank involves cut to the full depth of the teeth, so needs maximum rigidity.

Howard

[Author]

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