Rounding the ends of pullrods

[BufferParticipant @buffer]

Hi

On the loco I am building there are a lot of pull rods and cranks for the brake gear that need rounded ends. There are lots of different sized rods with different radius and hole sizes. Don Young says grip it with mole grips and radius with an endmill over a mandrel. I don't really like the sound of that. I have thought of making a plate with a peg and rotating them against a linnisher. Has anyone got any thoughts or good ideas, jigs, etc that will help to do this quickly and accurately.

Thanks

[BufferParticipant @buffer]

[DalboyParticipant @dalboy]

I made a plate with a dowel in it for making wheels on some of my wooden models in the past this made sure that a set of wheels had all the same diameter. If the plate was made of metal with a hole and various pegs made with the top of each peg having different diameters for the hole size then it would be possible.

The plate could have some method of setting the distance from the linisher belt to accommodate the different radii of the rod ends.

[Phil PParticipant @philp]

You could make some hardened filing buttons and use a selection of files with progressively finer cuts to get a good finish.

This should give you an idea of what I mean.

Phil

[egaParticipant @ega]

GHT suggestion for items short enough to be "hung" in the milling vice jaws from a rod through the pivot hole: make a series of cuts at different "hang" angles and finish with file.

[Anonymous]

Over the years I've used the following methods:

1. Filing buttons – I don't harden my buttons, but regard them as sacrifical

2. Clamped on a rotary table with the hole in the end of the rod over a pin in the centre of the rotary table. The centre hole in my rotary table is parallel, not Morse, so it's easy to make the pin

3. CNC milling

Of the three options 1 and 3 are the most used.

Andrew

[IanTParticipant @iant]

Mostly filing buttons Richard and where just a simple 'end' rounding is required, I also use my belt sander, which is very quick but not always quite as neat.

You can use a rotary table but the geared ones are not really ideal for it. I have a very simple rotary "table" (cum faceplate – about 2.5" diameter) fitted onto a bushed shaft that clamps under the tool holder. It can be clamped solid (for drilling) or rotated against an end mill via a lever at the other end of the shaft (much better/safer than twiddling the actual rod). It was very simple to make and just has some tapped holes in it to clamp the work piece. BTW – if you try this, you need to turn against the milling cutter – e.g. climb milling – so it helps to make several (small) cuts.

I've just checked and it must have been in my 'pre-digital camera' era, as I don't seem to have any pics of it and I can't currently find it. I vaguely recall lending it to someone, so it may not have come back. However, they are very simple to make, so I may well just make another one (and a certain law says I'll find the first one if I do so!)

Regards,

IanT

[BufferParticipant @buffer]

Thanks for all the replies. I might try the hanging in a vice option that sounds quick to set up then maybe the plate with pins on the linnisher.

Cheers

[JasonBModerator @jasonb]

I often opt for filing buttons on smaller items, you soon build up a selection that can be used several times before they become too worn ( I don't harden them) You can also use buttons on the linisher, just make sure they are retained well as the do spin at quite a speed. Ega's method can be used as a first stage to remove most of the waste .

Simple arbor with a threaded spigot that the part can be held on and rotated in the rotary table is the way I do larger items.

Now that I have the CNC that may get used more but probably in conjunction with making the whole part rather than just using it for rounding over.

Never felt happy about holding by hand or with grips/clamp against a cutter.

[Author]

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