Thread: Wickman OPG Optical Grinder.

Sure its flat Ray... just have to push down on it a little
As luck would have it I've been able to reuse the master I made for the lathe cross slide.

Hi Ewan,
It's the dovetail on the fix way of the wheel slide, though I'm not sure that helps you.

I've been using the shaper to cut the slot in the dummy spindle for the parallel tonight. I've roughed it out with a tool I got in a box of stuff off ebay but I'm going to have to rethink the grinding as the slot tapers about 1mm.


Stuart

After "only" 2:30 of machine time.
Going to have to find me some more 1/2 HSS.

Stuart

Touched up the gib side of the dovetail.
Pinned and bolted the ways to the casting and started touching them up.

Stuart

Pretty much good to go as a master I think.

Not a lot done today. Had to grind the ends of the dowel pins in the sliding ways as the ways have worn so much they were sticking up.
Then measured the squareness of the spindle to the ways.
Shapers make a great dial gauge stand
Set the parallel up, about 0.26 both ends.(ok 0.255 one end but lets not get to excited ATM )
Rotate spindle 180 and I get 0.24 and 0.28. Thats closer than I was expecting, calling that good for the minute at least.

Up to this point my masters have always been longer than what I was scraping. In this case my master is about 195mm and the ways I'm scraping are about 260mm. Can I just spot and scrap alternate ends?

Stuart

Tested squareness in the other plane. While getting an overly complicated setup ready I realised I just need to measure to the top of the dummy spindle. Hard to see but its without about 1/2 a tho.
Found a use for my magnetic blocks.

Did a couple of passes removing the high spots on the sliding ways then compared the spotting from the master and a straight edge. On one side they look pretty much the same. The other side they are a little different. I think thats all good but I'll need to have a little more thinking about that.

Stuart

Stu,

Why a slot that requires pinching to hold the parallel? Might greater accuracy been attainable if you had milled a flat cheek and shoulder on the dummy spindle? You would have had the option then of tweaking the fit with the scraper.

BT

ps Are those red handled thingos magnetic hold downs?

Hi BT,
I'm not sure I exactly understand what you mean*, but I think I get the jist. You mean to make the parallel square to the dummy spindle by design and then go from there?
I didnt think to much about that, it would require the extra steps of checking and tweaking for square. Though my way does require a little tweaking of its own to get the parallel parallel to the movement of the ways.

Now that you bring it up, thinking about it a little more, I'm not so sure either of the above is needed. If you just measure the ends of the parallel, turned the spindle 180, measured again. added the measurements from each end together. The difference between the totals is the error right? That maybe more accurate than either of the above methods?

Yes to the red handled thingos. Sure a couple of angle plates would do the job once clamped down......... but I'm been looking for an excuse to use these things lol

Stuart


*like a huge shelf pin? lol

Originally Posted by Stustoys

Hi BT,
I'm not sure I exactly understand what you mean*, but I think I get the jist. You mean to make the parallel square to the dummy spindle by design and then go from there?
I didnt think to much about that, it would require the extra steps of checking and tweaking for square. Though my way does require a little tweaking of its own to get the parallel parallel to the movement of the ways.

Now that you bring it up, thinking about it a little more, I'm not so sure either of the above is needed. If you just measure the ends of the parallel, turned the spindle 180, measured again. added the measurements from each end together. The difference between the totals is the error right? That maybe more accurate than either of the above methods?

Yes to the red handled thingos. Sure a couple of angle plates would do the job once clamped down......... but I'm been looking for an excuse to use these things lol

Stuart


*like a huge shelf pin? lol

Yes , shelf pin-ish Stu. You could have the parallel spaced off the vertical face of the cutaway allowing some adjustablity and the possibility of zeroing the parallel but you enjoy the mathematics so probably not much point.

BT

Well a little maths would have been easier than setting a parallel up within a few 1/10ths

More pictures.

I did some more scraping and was pretty happy with how it was looking until I put the straight edge on it again, looked like this.

I blued the straight edge off the ways I
m using as a master and got this, the straight edge a little light in the middle. But it would be (well not very much) all.(though maybe lighter still in the middle over the longer sliding ways)

So I'm thinking things must be pretty close .

I'll blue the straight edge on the large plate tomorrow and see what I get.

Stuart