Using the faceplate and dog on a Sherline lathe

[Chris TickTockParticipant @christicktock]

Hi, I am going through my Sherline lathe instruction manual on the various ways of holding metal. I understand how the faceplate and dog work holding metal between the two centres but my question is how would you get the 2 centres in the first place, if by drilling a hole what drill size and type?

Regards

Chris

[Chris TickTockParticipant @christicktock]

[not done it yetParticipant @notdoneityet]

This recent thread might help where it def says there is a morse taper in the spindle?

**LINK**

Just cut your own. Run the dog in the chuck jaws, not the face plate. Usually can use a drive plate on most lathes.

Edited to add: just cutting a centre in the chuck could be sufficient (for each separate job) and be driven against a chuck jaw or slot?

Edited By not done it yet on 19/08/2019 12:15:38

[JasonBModerator @jasonb]

Size depends on the work in hand but for a small lathe like that a BS-0 or BS-1 should be about all you need. For very fine work it is often a case of "picking up" the centre with a graver.

Work would be held in a chuck or collet with most insid ethe lathe spindle, if too big for the spindle then the free end would be supported with a fixed steady for drilling. or you can simply mark out the ends and drill with a bench drill.

For your Staff you would not drill holes but use female ctrs that the shaped ends fit into.

This photo from yesterday shows what NDIY is saying, a soft ctr turned to a point in te hchuck and the cranked dog being driven by the chuck jaw.

Edited By JasonB on 19/08/2019 12:27:33

Edited By JasonB on 19/08/2019 13:16:46

[Chris TickTockParticipant @christicktock]

Not sure I understand are you saying just centre using the 3 jaw chuck after checking alignment? If so what size / type drill to make a centre hole in tail end. Also what then is the purpose of the faceplate and dog as the 3 jaw can be used instead/

Chris

[JasonBModerator @jasonb]

Faceplates are more often used to hold odd shaped work that won't easily fir a 3 or 4 jaw chuck.

A drive or catch plate is a lot shorter than a 3-jaw chuck so allows you to get the max distance between ctrs as it does not protrude beyond the ctr mounted directly in the spindle

This size ctr drill would be durable, this smaller one is delicate and best kept for small work

 

Edited By JasonB on 19/08/2019 13:16:28

[Chris TickTockParticipant @christicktock]

thanks Jason would it be usual (as long as not detracting from end product) to drill deep enough to get a taper so to get more stability or just enough to get some baring?

Also as far as holding a longer bar steady to centre drill one could use the Sherline steady rest after aligning the bar for accuracy.

Chris

[JasonBModerator @jasonb]

Yes for slender parts that don't really need a lot of support you would not have to go right in with the drill and could stop part way up the 60deg part of the drill but you do need to go in past the smaller diameter pilot hole so that your ctr is bearing on a matching angled hole.

If the bar is too big to put through the lathe's spindle then yes a fixed steady or rest is used, this is one in action on something a bit bigger. You can also face the end of the bar with a setup like this as it is not good practice to start a ctr drill on a sawn end. Note as this was for a tool I have cut a small recess and then put the ctr drilled hole into that which saves the hole getting damaged which could throw things off.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Christopher judd on 19/08/2019 12:26:25:

Not sure I understand are you saying just centre using the 3 jaw chuck after checking alignment?… Also what then is the purpose of the faceplate and dog as the 3 jaw can be used instead/

Chris

Yes, because – within reason – the exact placing of the centre holes may not matter much. When turning between centres with a dog the axis of rotation is the line between the two centre points, nearly independent of any chuck run-out. If top accuracy or a known taper is to be cut it can be achieved by nudging the tail-stock sideways while testing with a DTI.

How easy it is to set and reset a tail-stock may be the sign of a quality lathe. The adjustment on my mini-lathe was distinctly crude and could take ages to get right. Not sure what a Sherline is like, but many lathe owners avoid altering tail-stock alignment if they can!

On a big lathe, centre drills are the best way of drilling the holes. They put a chamfer on the end of the hole that the well-greased centre runs on. Watchmaking may be too tiny for a centre drill in which case the centre is caught with the sharp point of a graver. As the centre of axis has no rotational velocity, the graver tends to find it.

Personally I've yet to use a face-place or a dog on any of my adventures. Much quicker to use a chuck or collet unless there's good reason not to!

Dave

[JasonBModerator @jasonb]

One point that may have been missed is that when using a soft ctr held in the 3-jaw you true it up by taking a skim cut and then DO NOT remove it from the chuck until all work between ctrs is complete. By turning it before use you remove any errors that may have been there if the chuck runs slightly off and this can be more accurate than using a ctr in the spindle's Morse taper as that could be slightly off too.

That crankshaft I use to illustrate my first reply was taken in and out of the lathe several times as well as being swapped end for end but as I did not take the ctr out of the chuck all my turning will be concentric

[Paul LousickParticipant @paullousick59116]

Christopher,

Answer to your question. " what then is the purpose of the faceplate and dog as the 3 jaw can be used instead"

If a work piece is turned between centres it can be removed from the lathe and put back on in exactly the same position each time. All 3 jaw chucks have some run out do not position the work exactly on centre. Adjustable 3 jaw and 4 jaw chucks with the aid of a dial indicator could get close but not as easily as using a centre hole on each end.

Paul

[Chris TickTockParticipant @christicktock]

Great help guys thanks very much. as always I struggle at first with the jargon but once the penny drops all is clear.

regards

chris

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