Chester 626 mill CNC Conversion

[Divided he ad]

Wile on the subject weee rant , rubbing something back and fourth on a sheet of emery paper is NOT LAPPING ,  another  engineering term that has been bastardized .

I always said flatting.... But I suppose that's wrong? Since it don't come out flat!


But I ain't changing my vid's... Flatting it is!


Lapping is for cutting 2 part together ain't it?




Ralph.

[NickG]

In the dictionary now it's either I think but as Rob said, I think probably originated from lapping together 2 mating surfaces so they fit each other. I think grinding in valves on a car engine was known as lapping? In these cases which is the lap though? I think the lap is the material in which the abrasive is embedded?

[Rob.Wilson]

Did I mention my Chester 626 mill was a crock of sh*t 


Decided to do a bit more checking this morning  ,,,,,,,,and it gets worse 

All blue areas are touches ,  Table to compound , 
 

Compound to knee ,,,,,,,,,,,,,what the fook !



Lets see if the Y is  parallel with the X axis ,,,,,,,,,,,,,,,,,,,what was I thinking .






Oh well , note to self , build complete machine next time 

Rob

[Stilldrillin]

Aaaawww....... Rob! 

But. Look on the bright side....... You're the Guy with the nous to fix it! 

Commiserations Mate.

David D

[NickG]

Well I've learnt one thing from these posts - never, ever buy a Chinese machine of any type again as I don't have the skill to fully rebuild a machine like you have. Terrible, people still turn out good stuff on them but imagine how good it could be with a decent machine!

[Rob.Wilson]

  David all I wanted to do was make new gib adjusters   

Hi Nick , I totally agree as this is bogstandard for a hobby  import machine, absolutely shoddy workmanship ,cheap crap parts ,bearings ,screws , fasteners all utter rubbish .
 I personally would never touch a far eastern  import ever again .  From now on sticking with used machines from  German ,Swiss ,USA and UK manufactures . 


Rob

[micktoon]

My heart goes out to you Rob ,
    its one step forward and two back when you find stuff like that...........it is sickening to think that when these things are made its more or less fraud really lol , they just make it look like a milling machine rather than work like one. I wonder how long they would last in a factory working shifts with contact points like that on the working surfaces ...................... What is your master plan to get around the problems Rob ?  Its not justice Rob but as David D says at least you will be able to overcome the problems, someone else with less gear and knowledge would now be thinking of scrapping the thing 
  I think all you can do is look at it as a challenge and think of it as character building     as they say  , while your watchers sit back  and wait knowing it will end up  in the end and we will have all learnt something on the journey , how to fix ...........as well as don't get one in the first palce

 Best of luck Rob and I hope its the last of the nasty suprises for you 
  Cheers Mick

[krv3000]

well rob it will be worth it in the end chin up it will run one day

[Rob.Wilson]

Evening Lads 


Well after a sausage sarnie and a brew I decided there was no way I was going to hand scrape a possible 20 thou out casting ,so it was whacked onto the mill for a skim.


Y axis



X axis


I just took the bare min of the faces , just enough to true them.

Try for flatness .




Test for parallel .





Thats a few tenths of a thou over just short of 12 inches .  0.008 mm , a tad better I would say 

Rob

[doubleboost]

Looks the dogs now mate
Have you ever fancied working in China

John

[krv3000]

lol by the look of robs ther still in the stone age

[Stilldrillin]

Well done! I had every confidence in you Rob. 

Especially after a sausage sarnie........ 

David D

[Mayhem]

Excellent work there Rob.

[doubleboost]

You need to get Bob to look at that clock
It seems to be "stuck"
I wonder if my mill is the same 
John

[Rob.Wilson]

I wonder if my mill is the same 
John

20 Tabs , a sausage sarnie and a brew I bet it is 




The fun continues  , with the compound slide all squared up it was trial fitted to the knee casting , as expected I knew i would have to machine some from the top of the Y dovetail , But the gap was not even  I could get nothing in one side and a .0025 feeler in the other , odd



so a bit measure up .

 


Oh well it need machining anyway . set up on mill using the four corners as reference points  to get it level both ways .I have to be careful of what gets machined away as it all has a knock on effect.   






with that done a light skim was done to true the face .



Now i checked all four corner points , all crack on .




now the middle , remember this machine was less than a year old when I bought it .




both sides have a nearly 3 thou bend in the middle and its not wear .its Fooking CRAP machining 




Rob

Edit : missed photo out

[doubleboost]

Nice set ups Mate
I like the machine jack
At least the new mill came in handy
John

[loply]

Rob,

Forgive my ignorance but isn't the surface which you appear to have machined a clearance surface? I thought the ways were the bits on the bottom? I can't imagine it's designed to contact both on the top (the bits you've written on with pen) and the bottom (the bit your mic gauge is sitting on), so what am I missing?

Rich

[loply]

Having looked at it more closely I think I realise that it is just a 6-surface bearing, must be complicated to scrape in!

[Rob.Wilson]

Hi Rich

Your correct the top is a clearance fit and dose not contact the compound , but because I had machined the compound bearing surface flat and true .

  they did  touch , as I new they would , I had to take 20 thou off the compound  , so I   machined the knee dovetail to clear the compound slide so the slide bearing surface can sit down on the knee bearing surface . Now that the top surface of the dovetail is flat I am just using that surface to shows how bent the Knee way bearing surface is .

I have to box clever here as I dont have much material to play with . Also pre made parts will have to be altered  I really should have inspected the machine before I started .  note to self there .

Rob

[micktoon]

  Hi Rob     what can you say , it looks like a case of what can you trust to be right in the first place to then use as datum point  , do you think any of this type of thing is due to them machining castings before they have time to season and settle the stresses out ? or they just machine them by eye and that will do for the quality standards they operate on. I am sure you will get it fettled in the end 
 looking on the bright side its making the effort you spent getting your new mill sorted out and making that flycutter..... worth every god dam second 

 Cheers Mick

[doubleboost]

Mick
Never mind season, they will be "machining" them still warm from the sand 

[Rob.Wilson]

Hi Mick

I never thought I would need the flycutter to fix the 626 , just made it as an in fill project , thought it may come in handy some day  , pleased I did make it now .

New mill is worth its weight in tabs .


Rob

[Jasonb]

So Rob given that all the flat surfaces were machined with a bananna cutter is it fair to assume that all the angled faces of the dovetails will no longer be true to your new flat faces and all have to be skimmed?

J

[Rob.Wilson]

Correct Jason , I will hand fit the dovetails . There is one saving grace in  that they actually got the dovetails parallel.


Rob

[Pete W.]

Hi there, all,

Rob,

I've been following this thread with interest.  I find the work you've been doing absolutely mind-boggling and I feel for you as you find each new problem.  It must be horrible to be sort of trapped by the work you've already done - giving up now would be enormously costly in terms of your investment so far.

The best I can say is 'hang in there!', I'd like to encourage you somehow, though I speak from such an inexpert level.

At least you have other machines to bring to bear on the Chester - imagine the plight of someone just having a dud machine and only their bare hands and a file and scraper or two!

It does give me an appreciation of the achievements of the pioneer machine tool builders, starting from very little and building-up to some of the huge but precise machines I have only read about and seen in pictures.  One such that comes to mind is the gear-cutting machine that floated in/on a pool of mercury to isolate it from ground tremors, was it Browns in Manchester?  I think it was that one that made/makes the big double helical gears for naval gearboxes.

Anyway, I say again, 'hang in there'.