DRO on radial arm saw

[Guineafowl21]

Thinking of this for my Wadkin BRA, for the rise/fall.

I use it a lot for tenoning, starting with the tenon too fat and dropping the arm until a good fit is achieved. Dropping the arm relies on gravity to take up the backlash, so I have to be careful to take up the slack with the handle. With a DRO, I could measure the tenon, and ensure the arm is positioned exactly 1/2 the excess width lower by dropping below the required setting, then raising.

I’ll need a 0-300mm range. Are the ~£40 read head/display combos on ebay any good? The only feasible mounting point I can see is on the pillar, above the table where sawdust will get to it. Will this be a problem?

This isn’t too serious a project, so I don’t mind throwing £50 or so at it, and maybe will be inspired to fit DROs to other machines too. Also, if there is such a thing as a rotary read head, I could feasibly fit it to the mitre setting of the BRA, and so get an accurate mitreing function (and, more importantly, a reliable return to 90*).

 

[Trevanion]

That's an interesting proposition, I've never seen it done on a radial arm saw but I can't see why it wouldn't work.

Do you really need a 300mm scale though? I'd be tempted to just buy a cheap 150mm digital caliper and rig up something off the column casting and the column itself. Although a nice Wixey Scale would be a proper job.

https://www.machine-dro.co.uk/300mm-12-wixey-remote-planer-readout-with-fractions

Not sure about a rotational scale, I'm sure there's such a thing but I haven't personally seen one.

 

[MJ80]

That sounds like a great idea, especially if there is one for the rotation. Could you bodge something up from one of those digital bevel/protractors?
I recently put a cheap one on my P/T and its working reall well. It doesn't have an automatic shutoff or a backlit display. The lack of shutoff will eventually catch me out with the batteries. I need to decide on its final position and sort out the cabling. At the moment its just on a block with magnets. It is set for zero by putting a piece through and adjusting the plate position on the scale with the two nuts on the threaded bar. A bit of threadlock to keep it all in position. The resulting thickness is pretty much as bang on as you could expect.
Have you seen the units with the flexible magnetic tape, they are more expensive but look like a good way of doing the table saw fence cheaply. I'm thinking about putting something on my moulder as I really miss the functionality it provided with my old machine.

 

[Guineafowl21]

0-300mm is about the height range of the saw, which I don’t use often, but it would be annoying to have to disconnect the DRO to get full range (or, more likely, forget to disconnect and break the read head ).

I’ll have a look at the cheap ones and give it a go. Not much to lose. An angle finder might work well for the mitre setting.

bscene-drinkingcheers:

 

[MJ80]

Its the cheapest one I could find that would give the scale on the thicknesser. It was about 25 euros from AliB. There are so many different versions and options available for such tempting money it makes upgrading affordable. Let me know how it goes with the BRA and I'll put it on my list of things to get round to.