D1-4 Cam Dimensions Query?

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D1-4 Cam Dimensions Query?

This topic has 7 replies, 4 voices, and was last updated 17 September 2018 at 00:38 by Martin Connelly.

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14 September 2018 at 20:31 #371753
Mark Slatter
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@markslatter13251
Hi all,

I'm trying to make myself a set of D1-4 cams to replace the dodgy Chinese ones that were supplied with my lathe. A number of forum members here have been very helpful in supplying the ISO standard drawings with dimensions (thanks again gents!)…however I can't determine what actually describes the cam portion of the part, or if in fact it is actually present on the diagram?! Please have a look at the section on cams from the ISO pdf I was sent. The cross section that shows the eccentric cam portion for the D1-4 cam is the bottom right hand one, the other views I'll include for good measure and the table of dimensions show what I have to work with.

The eccentric cam portion of the part is not actually cylindrical either, so apparently shouldnt be able to be turned on a lathe?

Also what is the "v" value of 250 degrees describing in the D1-4 cross section?

Any help would be appreciated!
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14 September 2018 at 20:31 #26185
Mark Slatter
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@markslatter13251
14 September 2018 at 20:34 #371754
Mark Slatter
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@markslatter13251
The order of photos and text got muddled up during posting, but the cross section view of the eccentric portion is above the text
14 September 2018 at 21:55 #371768
Martin Connelly
Participant
@martinconnelly55370
These tables are incomplete. At the bottom of the full table it states slope is over v.

Do a search for "madmodder iso 702-2" for the full pdf of the standard. I think they are probably made on some sort of CNC machine where the slope is relatively easy to program. Since there is a lot of variation in the values from one size to the next in the tables I suspect the illustrations are only vaguely correct for most sizes. It may be useful to do an accurate drawing of the size you want to make.

Martin C
15 September 2018 at 14:24 #371854
Circlip
Participant
@circlip
FULL PDF drawings were supplied. It is the Iso 702-2 -2007, corrected 2009. and superseded the BS equivalent.

Regards Ian

Edited By Circlip on 15/09/2018 14:32:13
15 September 2018 at 16:03 #371863
Muzzer
Participant
@muzzer
Pretty certain the eccentrics are relatively simple ie simple offset circular. I've seen Camlock spindles on US lathes from almost 100 years ago and clearly they would have used relatively "simple" machinery to make them. Besides, it's not likely to be hypercritical in this application.

I don't recall making mine in any detail but I know I made them in the lathe using the 4-jaw to get the correct offset. Once you have achieved that part of it, you simply need to place the tangential bore in the right position relative to that offset.

The Madmodder site files were probably posted by John Stevenson ie almost certainly the exact same ones.

I still can't figure out what the "v" angle relates to…..

Murray
16 September 2018 at 16:36 #372002
Mark Slatter
Participant
@markslatter13251
Hi everyone, first chance to catch up with the forums. I appreciate the feedback! As has been mentioned I did in fact receive the full ISO PDF, and this is what I copied the diagrams and charts from. I've started modelling up a part in CAD software and using the dimensions given it does seem as though the eccentric radius is free to "float" (i.e. the start and end points are defined in the charts but the radius is not given) and is not perfectly cylindrical, the non bearing surface of the cam being relieved for clearance I assume. However as Murray has pointed out it's probably not hypercritical as the camlock system allows a wide range for effective tightening.

I will get it eyeball close and cross fingers!

Many thanks again gents, it's appreciated!
17 September 2018 at 00:38 #372039
Martin Connelly
Participant
@martinconnelly55370
As the cam is rotated through angle v the distance of the working surface of the cam to the centre of rotation will change by the value given as slope. The curve produced has the same form as the spiral of a scroll chuck.

Martin C
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