Member postings for Dr_GMJN

Hello all, this is my first post here – and I know it’s long, but I want to include as much relevant info as I can, so go easy!

Last year I bought a Stuart10V castings set from the Doncaster show, and want to make a start on it. I promised myself I’d start machining (even just the base) within a year of purchase – that deadline expires on Sunday, but there are some issues…can anyone help me achieve my goal?

A bit of background – I have owned a Myford ML7 for about 12 years, I restored it after I bought it. I have done some basic bits and pieces on it, and some milling, but nothing really challenging at all.

I bought an SX2P Mini Mill last September, specifically for building the engine, and have only just got around to setting it up. I’ve added X,Y & Z DROs, a gas strut and adjusted the tramming and gibs as best I can. I’ve read several books on model engineering, and building the 10V, and watched numerous video series on youtube. I found Andrew Whale’s channel very good and he has given some great advice off-line.







Anyway, I’ve just machined some test pieces on the mill, and this is where the questions start…

1) I couldn’t adjust the gibs properly with the slides assembled, so I removed the leadscrews, locked one axis and adjusted the other. I tested with a DTI by rocking the appropriate slide. I got about 0.001” of play and couldn’t get it any better. I found that an Allen key was useless for this task – too springy, so I used an Allen bit. I also found that the difference between movement and locked was significantly less than 1/8 turn of the grub screws.

Question: I know I should aim for zero movement, but what is acceptable in reality?

2) I trammed the bed by mounting a DTI with its holder post in a collet, zeroing on a point on the bed, and turning it to the other 90 degree points over the width of the bed, and over the the equivalent length side-to-side. The diameter of the circle where the quadrant points were checked is around 130mm. The collet chuck was about 250mm above the bed. By shimming with steel, after a long, long time, I got each point to be within 0.001” of the zero datum point. I noticed that the needle moves beyond this limit if I pull on the column (not surprising I guess), but this will probably be representitive of cutting loads.

Question: I know I should aim for zero on all points, but what is acceptable in reality?

3) I started by milling some vice clamps out of steel. I found the DROs worked great in conjunction with a Starrett edge finder. Overall, for a first attempt I was very happy with the dimensions achieved. However, I noticed a series of lines in the milled surfaces of the block, which could be felt running a finger over the surface. These aren’t machining swirls. Polishing with a buffing wheel improved matters, but this is obviously not the answer from an engineering viewpoint. I assumed it was poor tramming, so I re-trammed (to get to the aforementioned 0.001” figure), and milled (conventional) a test piece. This was exactly the same. I then dressed the edges with a file, turned the block upside down, and repeated the process. Same again. I then measured the thickness of the block in 9 places. I was getting about 0.002” thickness difference. The block is about 60mm x 40mm x 16mm thick. I was taking about 0.5mm deep cuts with a 10mm diameter 2 flute slot drill (it’s all I have at the moment, but I’ve got some 4 flute end mills on order). I was using cutting oil on the surface as a lubricant. Speed was about 1500 – 2000 rpm. Feed rate “steady”. There was some noise and minor vibration. I also tried milling a piece of aluminium, and the effect is there but much less obvious.

Question: What can I do to get rid of ridging and dimensional error?

4) General questions: For my Stuart 10V, if I leave my mill as it is now with it’s current issues (if they are issues with this type of machine), will I be able to make my 10V to a good standard? In other words, it’s fine to want a perfect machine tool, but more relevant to me at present is “what accuracy do I need – am I chasing someting that’s not achievable with a Chinese machine tool”?

I’ve included some images below (I hope they will show up). Thanks very much in advance!