Machine Capacity?

[PeterE]

In the thread above about knurling tools it slightly diverged into machine capacity for a few comments (mine included), but as I do not want to hi-jack the thread further, I thought it was more appropriate to give it a thread of its own. I hope I put it in the right location, if not perhaps admin can move it.

Personally I got a bit surprised to understand that a small Unimat/MJ-189 is thought to only be useful for the softer metals but not steel, and then only in small dimensions. That is not my experience and perhaps not knowing that I have overloaded my small machine. But let´s take a look at what I have made on that machine so far.

My MJ-189:


First an example of a large turning, the aluminium disc at the back is 90 mm in diameter - as large as is possible to fit onto the spindle. Runs true and used for thin work turning where the job is stuck to the face using double-stick tape.


The second example is the foot for my version of GHT´s Universal Pillar Tool which is in fact a one-piece 70 mm diameter mild steel part - which was just about possible to fit into the 4-jaw.

It machined beautifully but took a long time to do as the diameter was larger than possible to run free over the x-slide. I first had to machine it down so the saddle/X-slide could pass.

All fitments to the arms of the UPT is done on the MJ-189 like the stem for chucks for example ...

... and with a fitted chuck ...

None of these items have posed any problems other than if I became over-enthusiastic with too fast feeds or too big cuts which normally resulted in broken drive belts - I have used a lot of those belts 

Quite early I found a need for a knurling tool and quickly found the scissor type ...

... the one I pointed to in my earlier comment on knurling. This tool has served me very well so far, but is now becoming a bit loose in the arms making them want to separate from the center line. With that tool I have made the following items from EN3-type steel.

Diameter from 25 mm at the top to 15 mm at the bottom. Also some brass knobs from semi-hard brass came out nice and was put on the boring bar holder I made for the MJ-189.

This holder is square at the bottom which is more rigid than the standard rectangular holder. The bar holes in the holder are drilled with the drill in the spindel and pushed forward with the saddle to get the holes exactly on centerline. 8 and 10 mm in diameter and a sleeve for the 6 mm bar (in the hole closest).

So from my point of view, the little Unimat/MJ-189 is quite a capable machine not limited only to the softer metals, but must of course be handled according to size!

So have I overdone it?   

BR

/Peter

[Jonny]

No you have definately not over done it, you realise its traits and work around it, well done.
On one of the chinese cheapy Conquest mini lathes i couldnt even spin polish 35mm larger dia than that!

[doubleboost]

I think you have done very well
As long as you have a feel for your machine and are not in a hurry it is suprising what a small lathe can do
John

[DaveH]

Peter,

Well done  just shows if one is good enough 

I have a Sherline lathe I have cut titanium on it and stainless.
 
DaveH

[PekkaNF]

You have done it great. know your machine etc.

Then again I had a Minilor TR1 lathe that I was able to spin and cut aluminium as large I coud chuck to it and did turn some bening 50 mm OD steel (firly free cutting), but it was not fun. This lathe is a fine example how lathe looks good and spesification has everything going, but they forgot to tell that although bed is cast iron, headstoc and all all the other castings are zink/ali/whatever but not iron metal. For everything only sharpest HSS honed to fine angle would do. Stainless steel rods, Copper discs of over 50 mm etc. gave me grief, it more fetting than turning.
http://www.lathes.co.uk/minilor/index.html

I could have got Myford 10 at the time with the same money, but trader was more eager to pagage more accessories with it and easy to communicate with...so I had shipped to me and it turned to a major disapointment. Modern chinese are better than that, although it looks nicer on the picture.

I have this lathe 10x18", which is a little on small side for me and it has some drawback, but it was a good starting point:
http://users.picknowl.com.au/~gloaming_agnet/cq9325rev.html

With this I can use insert tools and get chips out. It has faults, but modt of the time I feel that I'm turning and can get decent cuts. Drilling is chore, because tail has only 35mm of stroke and the tail stock is not really up to it. And power is inadequate on steel and over 14 mm of drills, has to resort step drilling etc. For most of the people this would be no problem, but what about if you have to drill long hole tempering steel rod? How many drills you are willing to break?

Last week I turned a back plate for a 160mm four jaw chuck and I felt that I was pushing it a little. I would have fitted 130 mm chuck if found one, but realsitic choices would have been 125 mm or 160mm chucks and smaller would have been harder to fit, because sizes of registers.

I was carefull and got things done but DOC was 0,2 - 0,4 mm at 160 mm dia and I could only get corly long swarf. Also belt would slip if I coaxed it any further. And I had to use pretty stout tool because cross slide would not approach close enough to the head stock (Not a problem if there were a chuck...). But honestly tool tip was allready outside of the front quide so no need to make an issue of it.

But I have learned a lot and one thing is that if there is a will (and skill) there is a way!

Extra size and quality will buy you some confort and maybe just a little conffidence, but most important is to use what you have now. Right

PekkaNF

[PeterE]

Thank you so much for kind words! I really thought I had overdone it and it feels reassuring that I can go on as I have started.

I am moving along in the same spirit with my SIEG C3 now and I am beginning to get to know it step by step. The C3 is as big as a Myford size machine but really not that substantial, something to remember when looking at accessories.

Sorry to hear Pekka that your first purchase was not up to expectations, that must have felt really disappointing, and then good to hear that the replacement machine really compensated well.

Regarding the knurling tool, I am about to make the more complex "sensitive knurling tool" from Hemingway. The bits are just waiting to be machined - after the small CES rotary table, my second version of headstock dividing attachment GHT style, and last but not least, the rack tailstock accessory has been made - phuhh 

BR

/Peter