A little inspiration for the duplicator crowd

[clemmy]

I happened across this, and found it very interesting. Particularly how the masters are enlarged. I imagine these were used in the Sisson duplicators.

Found on a Bagley Collectors site, from the collection of Bill Whitesell

 

https://thecolorsofbagleys.com/collections.html#worm

 

[Vodkaman]

Interesting. My method was a through rod (SS) with the lure master carved after drilling the block. Masters coated with D2T for hardness.

The craw gives an indication of the cutter used, must have been a fine round-nose mill in order to achieve that detail. I would guess that two cutters were used; one to rough cut and the fine mill for finishing. one cutter on each side for a single pass operation.

Dave

[Vodkaman]

This gives me some ideas.

The round-nose cutters are very expensive and lose their cutter edge, requiring servicing. The main cutter on my dup machines is a saw cutter, but this gives ridges. If I used a mill bit as a follower, I could skim off the ridges and add detail, also, the opposite positioning of the second cutter might prevent bounce, enabling a faster speed to be used.

Thanks for posting Clemmy

Dave

[hazmail]

I like the idea of the air line coupling for a quick change over- like you Dave I use a double ended staino rod (in  a chuck).

It also indicates that there was not a lot of load on the cutter head,,,  Just thinking, maybe there was a ''dead center'' at the other end, that would even things up a bit.

Also great picture Clemmy and thanks for posting.

Pete

Edited April 20, 2019 by hazmail

[Vodkaman]

Good point Pete, the load on the master must have been minimal. Another idea that I have been working on is a spring loaded counter-load on the master; to prevent bounce, reduce ridging, increase available speed.

I haven't started modeling yet, just collecting ideas. Another idea stolen from published dup' machines is anti-slop on the thread drives. I attempted to reduce slop, but not successful enough.

Dave

[hazmail]

Dave think CNC------------

''Ball Screws'', no end slop---& '' linear bearings'' no side play.

They are quit inexpensive, maybe not to ''CNC standard'' but perfect for our tolerances .

Lots of other stuff too, wire tracks, mushroom bearings , screw end bearings etc.

https://www.ebay.com.au/itm/Brand-New-Ball-Screw-1Pcs-SFU1204-250mm-1500mm-End-Machine-With-1Set-BK10-BF10/303039958559?hash=item468e96ce1f:m:mNnHLtd5W9N2Eqt-JCFnwPg&frcectupt=true

Pete

Edited April 21, 2019 by hazmail
add text

[Vodkaman]

Pete - I have been trying to avoid going down the precision screw road, thinking that such precision is not necessary if I can solve the screw/nut play problem. I think I have a workable solution for the next build.

If all fails, I have found an NC supplier locally. To be honest, I should be thinking along the lines of a full NC duplicator solution using a digital master. Instead of 60rpm, I anticipate 240 - 300rpm as a realistic cutting speed.

Dave

Edited April 21, 2019 by Vodkaman

[jonister]

240-300.. now we are talkin'!!

[hazmail]

On 4/21/2019 at 12:05 PM, Vodkaman said:

Pete - I have been trying to avoid going down the precision screw road, thinking that such precision is not necessary if I can solve the screw/nut play problem. I think I have a workable solution for the next build.

If all fails, I have found an NC supplier locally. To be honest, I should be thinking along the lines of a full NC duplicator solution using a digital master. Instead of 60rpm, ''I anticipate 240 - 300rpm as a realistic cutting speed.''

Dave

HUMMMMM!!

[Vodkaman]

Pete - Maybe 240 - 300 is a little optimistic. Five up/down cycles per second is going to set up a formidable vibration.

A realistic possibility would be to set up an equal and opposite force to balance out the vibration, a bit like noise canceling technology, but, straight away the design more than doubles in complexity. If the vibration canceling worked, then 300 would be a low number.

I wish I had an NC machine designer living around the corner.

Dave

[hazmail]

Yeah Dave, that's 5 times normal speed , but an admirable goal none the less  .

I went down this road too, but I was probably aiming for something in the 80-100 RPM range , I was trying to dampen the 'bounce' with mini oil over air shock absorbers  - didn't work, too complicated!! Then magnets sounded quite plausible, but never went there ??--I settled on 60 rpm and 2 cutting blades, a leader and finisher, still a work in progress---I also found lead angles make a hell of difference.

Using reasonably hard Mahogany & not Balsa tests speed and feed.

Pete