Chipmaster DRO installation

[swarfless]

I'm posting this little photo essay following a chance remark by PDW in another thread, forget where, that he had a DRO for his Chipmaster but was undecided how to do it. I agree, the Chipmaster seems to be designed to reject DROs & makes it necessary to make certain choices of more or less inconvenience .. sacrifices must be made. The pics should be self explanatory as to method, I'll just fill in the 'why's'. The anchoring of the topslide is modified because, 1) I'd heard several stories of Chipmasters/Bantams ripping the two teebolts out of the cross-slide, 2) I wanted to use a Multifix 'A' toolpost rather than an 'E' so raising it was necessary, hence the spacer (a disc of 1045) which is secured to the cross-slide via csk socket head Unbrako screws into 'cheekpiece' nuts that completely fill the cut-outs thereby maximising the amount of cast iron in shear. The spacer contains 4 caphead skt screws, pointed 60 degrees, at 90 degree stations & engage 4 teebolts dropping from the topslide. Those teebolts are made from M14 caphead skt screws & each has a radial 60 degree pocket for the pointed spacer screws. The M14s bear no resemblance to their origin, they simply supplied strong material. The 60 degree pockets are biased 0.5mm lower than the centrelines of the pointed screws to facilitate clamping action. capheads rather than grubscrews for better purchase not prettiness.Concerning the cross-slide scale, the pic shows the amount milled out, widening the original channel. I decided the gib screws needed sufficiently sporadic attention that covering them was the least inconvenience to avoid the more common rearward cantilever position some adopt.The long scale is mounted on a subspar milled from common angle iron, the appropriate legs shortened at the 15 degree of the Chipmaster bed's Copying attachment 'land'. Angle iron was used as it distorts far less than solid when metal is removed (less metal removed, less distortion). I have a Mimik copier to install, hence the blocks at the ends to take the template holder. Extra 2 holes in the TS end block are a mistake.Scale covers are cut from square stainless tubing, ends folded over & tigged, & dressed up. No extra holes were made in the bed, only the cross-slide needed new drilled & tapped holes for the spar & cover.The DRO is a Sony Magnescale .. obsolete now unfortunately.I should add here that about 2 decades ago PDW kindly offered to cut a new saddle pinion for me but I graciously declined coz I hadn't decided on how to remedy the excessive backlash to the rack. Eventually I made a new pinion shaft & scotch keyed a stock Hercus 14 dp 13 tooth pinion to it. Smooth as silk with sensible backlash the result.

[swarfless]

CORRECTION: The 60 degree pockets in the teebolts are biased 0.5mm HIGHER than the centreline of the pointed capheads .. silly me. Apologies all.

[lamestllama]

Hi Swarfless,

Thats a really neat installation and the photo essay is great. I would say a very similar install would work on a Bantam.

Eric

[swarfless]

Hi Eric, yes the only difference I'm aware of is regarding the attachment of the long scale at the back of the bed, which ought to be more straightforward being vertical & not at 15 degrees to? My only 'background' misgivings relate to the top-slide adapter, relying on the points on four 1/4" HT screws. A former work colleague used a different strategy on his Bantam, machined a circular T-slot in the top of the cross-slide & passed four T-bolts thro' the topslide base to nuts on top. He put a spacer under the toolpost. Thus far I've had no problems, the 'system' stood up to parting washers from 1045, 32 od, 13 id at 1500 rpm 0.14/rev dry without a whimper .. the 3 hp motor did notice it. Bit disappointed with reaction to the posting, expecting some robust debate. My display is too high (but had to clear the switch knob) & the scrawny support looks disgusting .. going to change it to a swinging arm for non-aesthetic reasons. I have made drawings of all details (I think), convertible to pdf if desired. They're not Drawing Office standard but workable.

[GJM]

Nice installation. My chippie DRO has the cross slide scale extending out the back for clearance. I will take some photos later.

[PDW]

Thanks for posting this - and others who have pix to post.

I still haven't gotten around to it, too many projects, but as the seasons roll on I'll probably be on the boat less so who knows - might happen soon.

For some definition of 'soon' anyway.

It's pretty clear that either I mill some of the saddle away for clearance or have the DRO spar sticking way out the back. Don't really like either alternative, hence at least one reason for the lack of progress.

PDW

[GJM]

Finally got some photos of my DRO setup. It was a quick job, but works well. China's Finest ex Aliexpress.


Chipmaster (1).jpgChipmaster (2).jpgChipmaster (3).jpg

The cross slide scale is a small size one. The standard size width and depth as used on the rear scale was to large to fit. THis is as i recall 18*20mm but I can check if it is important