Turned out nice

Thanks Martin, most appreciated.

Bearing in mind the restrictions of a smaller centre height and bed length of a 'mini lathe', I found it handled very like its big brothers at Axminster and I could carry out much the same exercises as I had been taught. It's rigid and (and having been right through and adjusted everything in sight, and a lot that are not) accurate. Pushing things a bit I know, but I successfully cut .5mm with a carbide tool (and LOTS of cutting oil and smoke) - not something I want to do regularly though.

There are limitations - the C3 is 9 x 30 while mine is 9 x 20, the centre height is the same; and the hand-wheel graduations are a little 'odd' - a metric screw is marked off in 40 divisions of a thou or 0.025mm, which doesn't quite add up and needs a bit of mental calculation.

It lacks (or mine does) locking of the cross and top slides, these are mods to be carried out. Also, look for tail-stock lever locking, using a spanner it a PITA. There is more than one mod for it though.

Consider a digital speed readout, or do what I did and buy a cheap tachometer. The motor speed control seems to be logarithmic - a lot of speed increase for little movement after about 300 rpm. Powerful though - no back gear needed and a minimum of 50 rpm.

You might also look at a quick change tool post as well. Save all that fiddling to get tools to centre height by pre-setting them. Also add this, and that - you do realise it's a money pit don't you?

Bear in mind that Arc have a lot of stuff in their catalogue which "is out of stock" - almost permanently. Have a look at Amadeal - brilliant to deal with for 'bits'. There's also an Aussie site - brilliant blokes.

Do I recommend it (depending upon what you need it for of course) - darned tooting I do! It's the most fun I've had with me clothes on since I pushed my sister into the gorse bush - at the bottom of the hill - in the snow.

daifly said:

I'm not anyone else 'cos it was me that started this thread but I am going on another 2-day course on Wednesday this week - this time an Introduction to Milling. I shall report back in due course!
Looks like neat work on the turning Phil. You've not forgotten Bob's teachings!
Dave

Click to expand...

Sorry boss - I was going to ask about the milling course - I'll look forward to your report before I contemplate it.

Oh no - Mr Rolf's instructions are my guiding light - usually just after I've done something that Bob suggested was not the best practice!

Have fun on Wednesday and say hello from me - the guy with the Unimat who breaks parting tools. Oh, and tell him I've got the missing laminated drawing. Ta.

Phil
Thanks very much for sparing the time to share your thoughts. You may realise if you've followed my other threads that this is all the result of a legacy left me at the end of last year. A lot of kits I'm never going to build, which when sold are funding the machine tools, this is likely the only opportunity I'm going to get in this area so I'm grabbing it with both hands. I have a Cowells ME90 which is a very fine lathe, so you might question why a Sieg as well. I think the answer is, because I can, there haven't been many occasions when I could say that. I'll keep the Cowells for the fine stuff and do the more general work on the bigger one.

I'm all too well aware of the money pit problem, since I had a lathe the milling machine was a recent purchase, and of the budget spent, 45% was the mill and 55% on tooling etc, I doubt the lathe will be much different. I plan to get 3 and 4 jaw 4" chucks, the 3" chuck supplied will go on the rotary table, I have a speed readout which will double up on the lathe, and a QCTP seems obvious enough. You mention a 0.5 cut with carbide tipped tool, have you considered indexable tools? Grinding HSS tools seems to be a major bugbear for beginners, myself included, so a pre ground tip looks a reasonably economic proposition, given the amount of work we are doing.

I can't say I've found the speed control on the mill to be too much out from linear, certainly nowhere near logarithmic, but it is on the brushless DC motor which may have a bearing.

I've had a look at Amadeal, didn't greatly appeal if I am honest, I think the SC3 from Arc is my preferred choice. Of course I'm in a happy position to spend within reason what I wish, a lot of my purchases aren't necessary to start out, so if anyone is considering a lathe don't let my choices and expenditure put you off.

I'm looking forward to hearing how Dave gets on.

Regards
Martin

I bought Mini-lathe from Chester a few years ago, when they had a special offer going. It has the 300mm bed, digital spindle readout and digital cross and top slide readouts.

It is possible to upgrade it with a brushless motor like the SC3 but expensive and not easy. I am currently having all nylon gears replaced with metal ones (I think with the brushless motor there is no Hi/Lo ratio gearset).

I have also gone for the Arc quick change toolpost and indexable tools which saves a lot of time grinding and height setting.

Would love a Myford but not the money or space, and probably overkill for 7mm. The Sieg lathes seem to be a good compromise.

Ken

Day 1 on the Axminster Introduction to Milling Course. Can you guess what it's going to be yet?

At the end of the first day, it looks almost exactly the same as the photo except that every face and end has been machined and dimensioned! We've used various work fixings such as vices and clamps, parallels, digital read outs etc.

Tomorrow - grooves, slots, V's etc.
Off for a beer now. This manual labour is tough for a softy like me!
Dave

daifly said:

Day 1 on the Axminster Introduction to Milling Course. Can you guess what it's going to be yet?

Click to expand...

A 'V-block' ? Your pictured set-up is great as it ensures the end can be truly square to the other faces. It also awakens the mind to other ways of holding a workpiece advantageously - other than making do with a vise. Axminster are to be commended for making the course available - and you for taking it.

Looks like some 'clearance' has been added (subtracted actually ) to the horizontal clamping bar at right

-Brian McK.

Ken
I would be interested to know the inserts you use.

Brian
Now I think about it a bit more, your so right, but does it depend on doing the sides before the end, or not? More thinking needed but all useful stuff.

Regards
Martin

Brian McKenzie said:

A 'V-block' ? Your pictured set-up is great as it ensures the end can be truly square to the other faces. It also awakens the mind to other ways of holding a workpiece advantageously - other than making do with a vise. Axminster are to be commended for making the course available - and you for taking it.
Looks like some 'clearance' has been added (subtracted actually) to the horizontal clamping bar at right

Click to expand...

Spot on Brian!

And milling one face:

We were encouraged to devise other methods for clamping our machined blocks securely so that we could machine the final end to give the correct 40mm length as well as squaring it up and that did not involve using the vice. This was the solution that I adopted. The 'clearance' that you refer to may be where I tried to ensure that the tip of the clamping bar applied positive pressure on the V-block near the work rather than than on the rear of the V-block which might have happened with an 'uphill' clamping bar position.
Another view of the setup before the final machining:

Lots of really useful and practical stuff about end mills, slot mills, cutting speeds for different materials etc.
Others on the course are from County Durham, Essex and Penzance so, if they can get here, so might some of you!
Dave

Martin Shaw said:

Ken
I would be interested to know the inserts you use.
Martin

Click to expand...

Martin,
If I may jump in at this point, I'd recommend users of small hobby machine tools not use carbide insert tooling until they are fully conversant with use of HSS (high speed steel) tool bits - and the grinding/sharpening of same. Carbide inserts generally have a tip radius 0.4mm and greater (there are exceptions) that is too generous and thus cutting over too wide a face for the power and rigidity of small lathes.

To my mind, early acquisition of a decent bench grinder with wheels no less than six inch diameter is the best thing an aspiring machinist can do. The key to successful machining is learning how to shape the tools that do the cutting.

Martin Shaw said:

Brian
Now I think about it a bit more, your so right, but does it depend on doing the sides before the end, or not? More thinking needed but all useful stuff.

Click to expand...

In Dave's photo of his milling set-up, the sides have been machined before the end. But irrespective, so long as the opposing side faces are truly parallel (before machining or not), then it follows that the ends will be square to them - using the set-up as pictured.

-Brian McK.

Brian McKenzie said:

In Ken's photo of his milling set-up,

Click to expand...

Might Ken possibly be Dave?
Dave!

daifly said:

Might Ken possibly be Dave?
Dave!

Click to expand...

Sorry Dave, didn't read far enough back in the thread

So was it Dave that carved a lump out of the clamping bar ??
All will go well now . . .

-Brian

Brian McKenzie said:

So was it Dave that carved a lump out of the clamping bar

Click to expand...

Ahh. I see now to what you were alluding! It wasn't me - honest.
Dave

farnetti said:

It is possible to upgrade it with a brushless motor like the SC3 but expensive and not easy. I am currently having all nylon gears replaced with metal ones (I think with the brushless motor there is no Hi/Lo ratio gearset).
Ken

Click to expand...

Yes, the brushless version doesn't have the Hi/Lo lever, the full speed range is available from the controller, 50 to 2500 rpm.

I agree with you with regard to metal gearing - Arcuerotrade sold me a set of metric gears quite reasonably - and then sold me the 63T gear to enable me to cut imperial threads as well - not that I have yet, but I could... They are a bit more noisy and I haven't yet investigated the cure. The nylon forward/reverse leadscrew gears are also very noisy and need replacing I think.

Sorry Martin, I haven't yet caught up with your threads - The Cowells is a nice machine and I wanted one when I didn't have the money, and then went the Unimat route when I did!

Now waiting for Dave's final report - there is a distinct tingling in the wallet.

Martin,

Part of the deal I got from Chester included a set of carbide tools so that is how I started off. I bought indexable ones after, Sumitomo I think from Arc. Brian is quite right in that they have a very small radius at the tip, so not useful for certain jobs. Since the start of this thread I had decided to go on the Axminster course as soon as I have finished re-building my new house next year as I am only 20-30 minutes away.

Phil,

I will be interested to see if mine is more noisy when the conversion is done. I am also replacing the 21/29 and 12/20 Hi/Lo ratio gears which involves taking the head stock apart, and at the same time replacing the headstock roller bearings for taper bearings. I would add that I am not doing this myself as it involves the use of another lathe and a bearing puller and press. Another member of my local area group is doing this for me.

Replacement metal forward/reverse leadscrew gears do not seem to be available in the UK so I sourced some from USA, I think the Little Machine Shop.

Ken

Astute followers will notice that this end of Day 1 steel block looks very like the starting item but every face has been milled and the dimensions are now as required by the drawing.

I'm happy with the size! Beginner's luck.

The next operations involved cutting grooves on opposite faces. The setup:

The grooves were 3mm deep and three cuts were made with the end mill, each about 1mm deeper than the last.

The slot was the next task. This introduced us to a variety of edge-finding techniques to ensure that the slot was both central and finished exactly 2mm from the end of the face. This cut was made with a single pass so the cutter first had to act as a drill before then cutting the slot and ending at the correct place at the far end.

A hole was then bored through the centre of the slot starting with a centre drill, followed by a larger drill before ending with the 3mm drill to complete.


More shortly
Dave

The next challenge/task was to make the large V. This required another setup change to ensure that the workpiece was held securely throughout. The drill under the nose of the clamp is to avoid crushing the edge of the previously machined groove and to facilitate the clamp pressure holding the piece.

The first cut took about a 4mm deep bite out of the work but as the cutting area increased, the depth was progressively reduced until each pass was removing only 1mm.

The end mill gives a good finish on the bottom of the cut but the side of the cut has a far less pleasant finish!

This issue was anticipated in the planning of the V cutting. The side of the V was left over size and then the piece was turned to put the chatter marks at the bottom of the cut.

These marks were removed as the V was finally cut to size. The previously drilled hole can be seen in the centre of the V.
The final task was to cut a 3mm deep groove in the bottom of the V. This was done with a circular slitting saw.

In addition to all of the setting up for each operation, there was a lot of time spent considering just how to safely and accurately achieve each cut and how to secure the workpiece. It's a lot more involved than I thought!
We finished the day with an introduction to the milling dividing head and produced a seven equal-sided brass bar from a round bar. A most impressive result.
Oh, and my result is below. My verdict on the course that it is an excellent introduction to the milling machine, to the use of a variety of machining tools and to some of the processes that need to be mastered to get the most from it.
Dave

I agree with Dan, nice job, and thanks for taking the time to give us the words & music.

Best
Simon

Dave
Most impressive, you extol the virtues of the course which are apparent from your finished item, I wish it wasn't so far away.

Ken
Interesting. Neil Wyatt in his book on the mini lathe suggests that there are certain indexable tips that will be satisfactory, a tryout in due course.

Brian
Thanks for the caution and whilst I understand that grinding tools is certainly a desirable attribute, many operators in modern engineering can't do it, they have no need. What is apparent is that there are schools of thought about the size of lathe and hence it's rigidity, as to whether imdexable tools will work. Since I have grinding wheels HSS is certainly a cheaper option to explore.

Regards
Martin

Prompted by Phil earlier in the week that Arc were offering 10% off internet orders, and might it not be a good opportunity to order the lathe, I could but only agree with him. So with a bit of judicious financial juggling, and SWMBO being in an agreeable mood, orders were placed. Parcelforce delivered a box of goodies today, and TNT are due to deliver the big box with the new toy tomorrow, so I'm unavailable for the next few days whilst I relive childhood Christmas expectations. Pics to follow. This has to be more fun than the stramash going on in the Guild at the moment.
Regards
Martin