Warco mini mill cnc conversion

[BillTodd]

I would strip the table and saddle off to check there's not swarf or other crap trapped in the dovetails. I would not expect these little machines to have tapered gibs, so any foreign body on the fixed side could cause the problem with giving a tell-tail loose gib on the other.

Bill

[buster]

BillTodd,
I just removed the saddle and examined the LHS dovetails and indeed the machining was not good. At the top of the dovetail was a small (0.1mm) of unmachined
ramp shaped metal 2/3 thirds the length of the channel. I scraped most of it away with a thin file and finished with off with 600 grit.
If I keep up this scraping process I will of course do two things - ruin the dovetail or get no near perfection!!!

I will reassemble the lot tomorrow and retry the previous laborious calibration setup again.

[buster]

I have reduced the XY error to 0.4mm max over a Y travel of 98mm but the LHS Y dovetail has now in my opinion been scraped too much. So anyone know of a reasonably cheap!
engineering firm in Bedford or surrounding area capable of machining this mini mill saddle.

I might consider travelling up to 50 miles to get it done,
Thanks for all your help.

[buster]

I had the saddle machined by a local company. They first measured the dovetails for parallelism and the results was not good. The fixed end was out by 0.43mm and the gib side was out by 1.05mm.
Both end were machined with a 30 degree dovetail and the results are truely wonderful.

On the machine I now get 0.03mm worst case after lapping the gib on the y axis and making slots for the set screws. In addition I replaced all the 0.125mm balls in the ballscrews with 0.1268mm and this has achieved 0.08 backlash.

I thank you all for the helpfull replies.

[irving2008]

Who did it and how much did they charge?

[buster]

http://www.constant-precision.co.uk/ based in Kempston Bedford. They did it in less than 2 hrs and charged 30 pounds.

[irving2008]

wow... well bedford's only a short drive up the motorway from me. I don't know if mines that bad - need to measure it. but before i do the CNC'ing work, while its all in bits I may get that sorted if need be. Mines a tad bigger and heavier...

[lanc101]

Hello Buster,
Ive just stumbled across the same problem with my mini mill and found it extreamly interesting reading your thread. After machining a 100 mm 'square' sheet of aluminium and checking it for square I found my mill was .2mm out of true and like yourself assumed the dovetails on the saddle are machined out of square to each other. can you please inform me as to the engineering company you used to have the saddle re machined as I live not too far from Bedford.
Thankyou
steve

[John Wright]

Hi Steve

I used Constant Precision, the same machine shop that Buster did in Bedford. They still had the mill set up for his machining and did it while I waited. They were very reasonable and helpful.

http://www.constant-precision.co.uk/

It was such a nuisance that the dovetails had been machined so innacurately, but the cure was quick after I removed the saddle. I discovered my problems before I fitted the ballscrews as I saw a thread about innacuracy with the mill.

Now it has been done I get very good results and have used the mill for several jobs since then.

This video will show you one of the tests I did. I know it is painfully slow machining, but of course I have faster speeds set since then.

http://www.youtube.com/watch?v=qRpMx-qp5ik

John

[lanc101]

Hello John, Many thanks for letting me know about Constant Precision and I will certainly give them a call and hopefully they will re-machine my saddle too. Im very glad you got your mill sorted out in the end and I suppose there is a moral in this story for us that you only get what you pay for however it seems that once this re machining is done the mill is then perfectly accurate.I will keep you informed how I get on,once again many thanks for replying to my question.
steve