Setting up a Mini Mill & Stuart 10V Machining

There is not much of a machining allowance on some of the surfaces so you will be doing little more than skimming the surface.

The thin sections throw up their own issues with the possibility of being chilled as the small parts, corners and edges cool rapidly and form a hard iron but carbide usually copes with that, at least for the initial milling if not drilling and tapping near corners.

I see, thanks.

I made the second clamp this evening. Somehow it took me twice as long, had the same issues, but as a bonus, I made a mistake on measurement, so one of the overhangs is 1mm too long. Onwards...

Well I had a pleasant surprise, reading above the tramming of the SX2P I thought I would check mine as is quite some time since I did it last and the mill has done a lot of work since.

Y reading across table edge to edge 5.5" = 0.0002" X reading across 4.2." each side of table centre = 0.0008". I don't think I will complain about those readings.

GMJN, one tool I would recommend for your SX2 is the ARC 25mm 2 insert end mill. It takes coated inserts for steel and uncoated for alu etc, it really is excellent I use mine all the time on parts large and small. Great for facing and reducing thickness and the finish it leaves is excellent. Its about the perfect size for the SX2 and the mill doesn't have any issues driving it, very good price to.

Ron

Edited By Ron Laden on 08/05/2020 10:04:47

Thanks Ron - did you try moving the head with your hand while checking the tramming? I'd be interested to see what your thoughts are on any deflections you might get?

I'm getting a list together for an Arc Euro order. I will look at the end mill you suggest. In terms of Fly cutters, I'm thinking of getting this one (when it's in stock again), and using my Sandvik 8mm left hand tool holder with it:

https://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Fly-Cutters/Fly-Cutter-Holders-Taper-Shank

Any comments?

Thanks.

ETA do you mean this one in R8?

https://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Indexable-Carbide-End-Mills/90-Indexable-Carbide-End-Mills

Edited By Dr_GMJN on 08/05/2020 10:40:47

Not so much a comment as a suggestion. There is a thread for practicing posting in. If you have got a web page copied to the clipboard to paste in a thread then use the link icon to create an active link. It is the one that looks like three chain links with a globe behind them. You can paste your link and give it a suitable description.

Martin C

Test thread

Link added

Edited By Martin Connelly on 08/05/2020 11:12:37

On the subject of fly cutters I tend to use my smaller ones similar to the plain shank set of 3 that ARC do and the taper shank one gets used once in a blue moon. Easily held in an ER or R8 collet

Thanks Martin, I would edit the post, but the edit button's disappeared.

Hmm, it's on this post. Do we only get one chance to edit a post or something?

Edited By Dr_GMJN on 08/05/2020 11:25:24

Wouldn't the R8 version gain me some a bit more stiffness, or would you consider it too large a diameter (it's 63.5mm vs. 35mm for the plain shank version)?

Yes, Ron meant this one 060-282-00258

Ketan at ARC.

Yes sorry, its the R8 one Ketan added a link for above.

Ron

For that size of work I think the R8 may be a bit large, infact the most used one of the three I have is 30mm and I use that with a 6mm HSS bit set to swing just over 50mm dia.

Rigidity wise I doubt there is much in it with the larger cutting radius cancelling out the more solid R8 body/shank, with the smaller radius you can also run the spindle at a higher speed for the same cutting speed at the tip which helps keep the motor in it's power band and

No I didn't try moving the head so to answer your question I set the DTI up, centered the table and measured 100mm each side of centre in X. Pressing hard down on each end of the table I had movement of 0.0012" one side and 0.0015" on the other.

I then centered the DTI on the front edge of the table and whilst pressing down on the table I pushed the top of the head back as hard as I was comfortable with. The reading lifted 0.0025" and it was similar dropping 0.0027" when I pulled the head.

I expected there would be movement as it is a small hobby mill but it was better than I thought it would be. Am I worried about it? not at all the machine produces parts to the dimensions I am aiming for and gives a good finish.

Your machine is now trammed just use it, with some half decent tooling it will be fine..

Ron

Thanks Ron, much appreciated.

Yes, tomorrow is D-Day in terms of making a start. And make a start I will, although maybe only some preparation on the box base.

I am waiting for delivery of a fly cutter and some new end mills (ass suggested by folks on here) so I'm starting from a known baseline in terms of tooling. Once I'm happy using those, I'll make a start on the machining.

Ok another one:

I made the first bit of fixturing for the 10V - a simple rectangular piece of unhardened tool steel about 5mm thick, with two holes in it.

I began by mounting the sawn piece on a long edge in the vice and face milling the other long edge, then turning it through 180 degrees and repeating the process. No problem at all. Quiet, smooth machining, nice finish and parallel to the limits of what I can measure.

Since I wanted the piece to have square ends, I thought I'd simply turn it 90 degrees, and mount it flat in the vice, on parallels, and side mill the short edges. This was hopeless (as it was with my vice clamps). I got a load of noise and chatter, and terrible surface finish. Cut depth was about 0.5mm. Steady feed. I was using a 4 flute slot drill.



Any comments? Cheers.

Assuming it's not a cheapo cutter there are a couple of possible reasons:

1. Too slow a feedrate, with shallow depths of cut you can really ramp up the feedrate, search for chip thinning to see why. With a 4-flute cutter I'd be feeding at more than 500mm/min assuming the cutter is carbide and is running at 2000rpm.

2. Climb ,milling will generally give a better finish, especially in sticky materials like some low carbon steels, in particular EN3B.

Andrew

But with your mill, climb milling might be a tad courageous unless you have the gibs very tight. Problem is that the cutter force pulls the work into the cutter if there is any backlash in the leadscrew so the cutting depth suddenly gets much bigger. Common practice with cnc and if you have ballscrews, but not so common with a manual mill with conventional screws.

Oh dear, and I've just done it on some hot rolled plate.

Andrew

The cutter is a Sandvik 12mm slot drill, used only a couple of times on aluminium.

Regarding feed rate - I tried slow, and fast - fast like I was in in a comedy film. Same result.

No way I'd try climb milling on my machine - I did it once by accident, but wont be doing it again - the backlash in the leadscrews is terrible even after adjustment.

Better learn to draw file then.

Andrew