Member postings for Ross Lloyd 1

Hi

I would like to get down to doing some threading on my lathe which I have had for a while, its a Warco WM250V. I usually use 12mm shank tool holders and inserts, though am not averse to grinding my own out of HSS! At this stage its just for practice.

I would be looking at threading on aluminium (I have 6082 at the moment) or mild steel mostly.

Do I need two separate tools for ally and MS, or can I do that with the same kind of tool? I know alu tends not to want to break into chips too readily after some... fun experiences with turning!

Is there a tool you have had good experiences with / specific supplier?

Cheers!

Hi all

Thanks very much for all the responses and the effort that went into them!

I think the tool being slightly too high sounds like the most likely cause as I wasn't massively scientific about it. I had a little shim in there as I don't have a QCTP so maybe next time I will take a piece of it out. It certainly does seem that parting is very sensitive to setup, so its a good bit of learning.

To answer some questions, yes definitely mild steel - EN1A.

I will definitely look into a tool height gauge, thanks again!

I had a small 12mm thumbwheel, drilled and tapped to M6, sitting in a collet chuck and still attached to the stock. Mild steel, 15mm bar stock.

I trued up the parting tool, ensured it was flat to the work and checked centre height against a drill bit that was already sitting in the tailstock. I applied oil from my lathe oiler gun, a light engine grade oil. This set up usually works fine for me.

I started parting, lower speed than for turning as this is the general advice I have received. The parting was going just fine, nice smooth layers of metal coming off. This was around 300 rpm. As the diamater was getting thinner and it seemed the lathe was having to work a bit harder, I thought I would stop the cut and increase the speed slightly, to about 450rpm.

However when I went back to finish the cut, the tool only rubbed. I tried putting the speed back down. Then back up further. No luck. Applying a little more pressure and I heard a "crunk", and the final < 1mm wall remaining between the thumbwheel and its hole had deformed.

I thought maybe I had blunted the tool, but checking it on the parent stock showed it was fine.

Why might the tool have refused to cut when going back the second time?

Should parting off operations always be one smooth movement?

Thanks for reading!

Thanks Andrew

Thank you, quite a trove of info there

Thanks Andrew,

When I spoke with Warco, they said it would void the warranty only if I made extensive material changes to the machine. That is why I am asking about the potential need to mill off metal for clearance (I am not sure on which part) which was apparently needed in the old versions of the WM18.

Cheers

Hi Nick, thanks for the reply. I have looked into that machine and numerous videos of the conversion, and whilst it is similar, it appears to be the equivalent of the WM16, one model smaller than mine. Though the general idea will be the same, obviously the kit parts would not match. Thank you for the suggestion though.

Hi

Further to my CNC quest this board has been so helpful with so far, I have seen some old posts here as well as the Model Engineer article about converting the WM18 to CNC.

The 4-axis + high speed motor job Roger has done looks amazing, but there are no plans or drawings as such. Not a criticism by any means and as he points out, setups vary and he figured it out on the fly.

However being slightly time-poor, I was wondering if anyone knows of a source of plans / CAD models etc for converting the current WM18 model, or very close equivalent, assuming changes have been made over the years?

One older post here mentions needing to machine something for clearance, I am hopeful that is not still the case as I also have a concern that extensive modification will void warranty. I know some drilling will be needed for limit switches and such but I would like to avoid major surgery!

Thanks for reading

Thank you for all the input gents

After much toing and froing and taking into account the advice here, I am now starting to lean back towards converting the WM18 again, based on the articles ran in Model Engineer.

Will probably make a new post to ask more!

Cheers

Hi

I already own a manual mill and lathe (warco Wm18 and warco WM250V)

I am now looking into buying a home CNC and the one that springs to mind is the tormach PCNC 440.

However, I see there is no UK or europe dealer, and as a result must factor in import costs. I think this boils down to two questions then really:

1) Has anyone recently imported a PCNC 440, that can provide an all-in cost for purchase and import duty / VAT / shipping / other hidden fees?

2) Are there alternatives? I looked at the Sieg KX1 but note arc euro trade dropped them as they are too hard to support. Are any of the Wabecos comparable to the 440? I would say all of the Haas's are out of my price range (their quote and price list pages refuse to work for me), lets say max £7000.

I could convert my WM18, but I'm not convinced I will end up with something too great as a result.

Thanks for reading

Edited By Ross Lloyd 1 on 24/06/2019 16:15:51

I am wondering if I weakened it with the method I used to install the tip. I could not find anything online about the correct way to install the inserts, so I placed it in the lathe, then held a small cylindrical piece of stock between the insert and a workpiece I had in the lathe. I had the cyclindrical piece sitting well below the tooltip and then applied pressure on the cross slide to push the tip into the holder. Could this have weakened it?

I bought the holder and insert from RDG: https://www.rdgtools.co.uk/acatalog/Indexable-Parting-Tool-3mm-x-19mm-blade--12mm-shank--2535.html

Cheers

Ross

Edited By Ross Lloyd 1 on 17/01/2019 12:23:23

Thank you

Hi Jason!

Thats interesting to hear, I have heard the WD40 recommendation before, sounds like its time to nip down B&Q.

I need to learn these insert acronyms too, is DCGT just the specialised alu tip discussed above?

Thanks Dave, do you mean uncoated carbide? Thanks!

Ross

Thanks Vic! Do you have a preferred supplier? I am using the DCMT 07 diamond insert at the moment (not sure if it comes in different sizes depending on toolholder?)

Hi Clive, many thanks for such a detailed answer. I have definitely seen the built up edge you mention, its glint caught my eye as I brushed off some chips! Yes the heat is a pain, especially when a long snake of hot swarf decides it wants to meet your hand.

I will try sharpening up one of my HSS toolbits and see if I get on better with that, otherwise I will try out some of those fancy alu inserts. Thanks again!

Thank you Chris!

Oops yes brain fart, 50mm. I have a copy of machinerys handbook, for ally it said 680 opt, 2080 avg for the cutting speed. As the speed / dia charts dont go up that high I just interpolated for the rpms. That said I now wonder if I made the same cock up with the diameter. I will go and check!

Thanks for replying

EDIT: Actually tell a lie, I was thinking about the turning I did after. I just went with 350 rpm to start and increased to 700. Perhaps I have missed it but I have not seen a specific section in machinery's on parting, and generally halve the turning speed on advice from Toms Techniques (youtuber)

Edited By Ross Lloyd 1 on 17/01/2019 10:20:43

Hi

I am having a bit of trouble turning 6063 ally. Ibought a nice new DCMT 07 insert and holder, which cuts amazingly well on mild steel

However with the aluminium it whines, it gets very hot (turns the shop into a bit of a steam bath when using oil ) and the chips birds nest badly.

I have seen specialist inserts for alu with much sharper raised edges and chip breakers and a different coating (silver colour vs the 'brass' tone of mine, titanium compound?). Is it worth getting one of these or is there some art to making a regular carbide insert get along with aluminium?

Part was 50mm diameter, started with 350rpm and increased to ~750 rpm. Tried 0.4 - 0.8mm depth of cut and experimented with tool angles. It seemed a little hit or miss, sometimes the chips broke nicely. It always whined and ran hot though, kind of a constant high pitch like tinnitus as opposed to the obvious rubbing sound I've heard in the past.

Or should I try HSS?

Edited By Ross Lloyd 1 on 17/01/2019 10:07:16

Thanks for all the replies, in the end I went with the RDG holder with 3mm insert. Am already seeing some of the things you guys mentioned, I was running it through aluminium, 500mm diameter. After the second parting operation the tool was blunt and had lost its edge, not sure if I was running too slow for ally / carbide. I started at 300 rpm and gave it a bit more juice to around 700, I didn't want to go too high though as it was quite a long piece of stock being held in a steady (basically cutting it off due to my vice being broken and couldnt hand saw it).

I understand ally is more of a pain to deal with anyway. Should I have been running 1200 rpm or something? Before it blunted though, as long as I gave it a good push to avoid rubbing, and used plenty of oil, it cut really nicely.