Mount Trapezium

[Kim]

You are being a little hard on yourself there, those look like great silver solder joints to me! 

Kim 

[crueby]

I agree with Kim!  One trick that can help with that sort of thing is to take a sharp pointed rod and run it along the joint when the solder is flowing, that will disloge any bubbles and soot grit that may be there. On a long seam I do that to help the solder even out and flow, preventing thicker puddles. Its coming along great!   

[PaulR]

Those joints look great to me.

[redhouseluv]

I agree with Kim!  One trick that can help with that sort of thing is to take a sharp pointed rod and run it along the joint when the solder is flowing, that will disloge any bubbles and soot grit that may be there. On a long seam I do that to help the solder even out and flow, preventing thicker puddles. Its coming along great!   

Okay that makes sense - I've managed to 'fill' the holes with the soft solder now, but yes, gradually getting there.... thanks

[redhouseluv]

How to make soft jaws?

I made a start on the cylinder cover and have completed the top side. The build log states that I have to now cut the spigot off and hold the cover in some soft jaws to machine the boss which protrudes into the cylinder

1. I haven't any soft jaws, but that's was easily resolved as I ordered some
2. I have never made or used any before

I presume I have to hold the work by the outer diameter not as why else would you need soft jaws? How do I machine them to fit and they must be very shallow given the thickness is only 0.080"

[Jasonb]

Put the jaws in the chuck and grip a piece stock that is just larger than the raised diameter insife the stud holes and set back a few mm from the front. Now just imaging you are machining a 1mm deep hole into a solid piece that is the diameter of the cylinder cover. Use a sharp tool so that you don't leave a radius in the corner of the cut.

Loosen the chuck and remove the 12mm stock and you can now grip your part pushing it back against the 3 jaws which will stop it wobbling.

[redhouseluv]

Thanks - I'll need to have the jaws in hand to fully understand what needs to be done, but I kinda get it. I guess I only need the minimal amount sticking out from the chuck sufficient to clean it up having machined the cylinder boss to diameter and length.

[Charles Lamont]

The alternative to soft jaws is a split ring. This is first shouldered on the outside so that when turned round it sits against the face of the chuck jaws. Setting up in the second position, make a note of which chuck pinion you used, and make a mark on the ring against No.1 chuck jaw. Now turn a shallow rebate on the inside a snug fit on the flange. Take it out of the chuck and cut it through radially with a hacksaw. Put it back in exactly the same position and use the same pinion to grip the job in the ring. This works even if the chuck is not very true.
 

[Jasonb]

I'll take some photos of my soft jaws later.

Although you can machine a recess every time a job comes up I have found that just two recesses do me for most things as their main use is to provide a back stop rather than get the work running concentric. It does not seem to matter if the machined recesses are a bit smaller or larger than the actual item as they grip much like the outside jaws provided with your 3-jaw chuck but are just shallower stepped.

[Jasonb]

Here you go. First pic shows the two recesses I have in this set of jaws which do me for 99% of my soft jaw work. If I were doing them again today I would probably go for 40mm and 60mm but I did more imperial work back when I first cut them. I can hold from about 25mm to 75mm  with them.

Second photo shows a bit of barstock held a few mm back from the end which allows the jaws to be machined in a "tightened" position.

Third shows the boring bar setup with a 0.2mm radius tip or a HSS one with no radius will do.

[redhouseluv]

Again, pictures tell a thousand words, I got it, thanks Jason

Charles I have heard reference to a split ring before, but never quite understood what it meant, thanks for the diagram - what material is the ring made from?

Just waiting on the postie ....... again! 

[Charles Lamont]

A split ring can be made from  free-cutting mild steel or whatever else you have to hand.

[redhouseluv]

Soft jaws arrived, machined 2 steps into them like the pictures above. Was very wary of how much was actually gripping, but held it perfectly and the result is below

[Jasonb]

I tend to try and stick to no more depth of cut than half th egrip length which should not pull the work out of th echuck. You can grip quite large bits by very little.

[redhouseluv]

That's good advice, thanks - I was took very light cuts as am just not used to holding work in this manner. Impressed by that large chunk you are holding in the picture, visually it doesn't seem like it should work, but clearly does