Tos FN22 milling machine (Deckel clone)

[Pete.]

I could not help myself I had to scrape out that half thou taper. I got to thinking that since the most of the wear I scraped out was at the front, being already slightly tight at the back would only get worse with wear. So I got it down to a tenth or two (hard to tell when the needle reacts that much to the scrape marks). The Y slide now moves very smoothly with no evidence of tightening up as before.

Dropbox

www.dropbox.com

 

[addjunkie]

What will this be used for once its better than new and reassembled.

 

[Pete.]

What will this be used for once its better than new and reassembled.

It'll be on standby in case JWST needs a new mirror in a hurry

 

[Pete.]

I wanted to check the geometry as a base point but I found that whilst the y-axis gave repeatable results the x-axis which was not yet scraped in any way was quite variable due to the wear. To get some sensible results I decided to rough-scrape it at least good enough for decent measurements. No point finishing anything until I could work out which way each axis needed to be 'pitched' but that will come later with little effort.

Table flat ways first. I did several rounds until I was left with just a couple of wear patches.



I mark out each patch of no-contact and just keep rough-scraping around them until they eventually disappear.



Once I have blue spots all across the faces I know that I'm less than half a thou away from dead flat.



I put the table on the vertical slide and was still getting spurious results. Even though it should be returning fairly consistant readings but just pushing and pulling on the table had the readings moving about. I tried to print the angled ways but the straight edge was hinging on the middle of the way and not printing at all which is very odd - on these ways all the wear should be in the middle. I broke out my cobbled-up dovetail gauge to take some readings.

Set the gauge up like this. The two tubes are designed to bear on the flat and angled ways only and the foot sits on the opposite flat way. The tubes can be reversed for inside or outside dovetails.




The dial gauge reads the difference in gap between the two dovetails. It doesn't tell you if either or both is straight (the might both be parallel and both out of straight) it only tells you if the gap varies.



Here's the results:

The middle of the ways are around about 3 thou narrower than the ends. That makes the slide rock on the centre point. I'm going to have to think about what I'm going to do with this. My first option would be to get a 55 degree dovetail cutter and mill both sides parallel and aligned with the table tee slots. Sadly, I don't have such a cutter so I'm going to have to either make or buy one if that's the route I am going to take. Once milled I can scrape them into truth and then if I get it right I'll be able to turcite the gib which will sort that problem out too.

 

[awemawson]

Pete years ago I made some custom dovetail cutters from mild steel with slotted in and clamped HSS tool steel. They were just for a light finishing cut on the slides of the new top slide for my Colchester Student.

I’ve probably still got them so when you come down to make those gibs I’ll try and dig them out, perhaps you can make something similar.

 

[Pete.]

Pete years ago I made some custom dovetail cutters from mild steel with slotted in and clamped HSS tool steel. They were just for a light finishing cut on the slides of the new top slide for my Colchester Student.

I’ve probably still got them so when you come down to make those gibs I’ll try and dig them out, perhaps you can make something similar.

Very kind Andrew. If you still have them and the cutting edges are long eough I could nod the head to get my 55 degrees. I have a Bantam gib here somewhere I will measure the angle on it.

Of couse if I machine these dovetails just the right amount I can just fix the turcite to the gib and scrape it so there will be one gib less to machine

 

[awemawson]

I've had a quick look @Pete. but it's not where I'd have expected it to be - probably chucked out eons ago.

But it's construction was trivial - a dovetail angled piece turned from the solid with a suitable shank, with a cross milling slot to receive a bit of (probably) 1/8" tool steel plate clamped with a couple of grub screws, and the cutting edges ground on the Clarkson T&C grinder after fixing. It was fine for light cuts.

 

[pressbrake1]

I’ve modified dovetail cutter angles by grinding them in a spin fixture then manually relieved cutting edges with a die grinder. Cast iron isn’t too fussy
These days I’ve got the planer

 

[Brad93]

Makes you appreciate the work that goes into a machine the size of your devlieg Clive

 

[Brad93]

I’ve modified dovetail cutter angles by grinding them in a spin fixture then manually relieved cutting edges with a die grinder. Cast iron isn’t too fussy
These days I’ve got the planer

View attachment 343254

What sort of tolerance does that hold? Grind Alls as serious money

 

[pressbrake1]

What sort of tolerance does that hold? Grind Alls as serious money

More accurate than you can reliably measure in a non temperature controlled environment

 

[Pete.]

I rooted about in my stash of cutters and found a 60 degree one which had flutes long enough to cut the angled ways in a single pass.



I turned up a 7/8" arbor for it and gave it a knurl so I could press the cutter on and off for the time being. Mounted it in a 1" long-reach collet which I put in the Clarkson T&C holder set at 35 degrees down angle. I dressed in a smallish wheel because anything bigger would foul the collet before cutting the whole flute. I used a hacksaw-blade stop on the gullet of the flutes to index the 20 flutes for cutting.



Once the flutes were all re-ground they had gained a very wide land on the primary cutting angle especially at the top where the most material had been ground off.



This is bad because if the primary relief is too wide the trailing edge of it will drag on the surface you just cut. I had never ground one of these types of cutter before and I was running out of time so I eyeballed the angle for a secondary relief to thin out the primary land.



It's done the job and ifI need to do more I will give it a lick with the mini grinder. So long as I keep away from the cutting edge it'll be fine.

Here's the cutter offered up to the job.



So hopefully I'm off to Andrew's tomorrow to stick it on his Bridgeport and straighten up these ways.

 

[Sean64]

I rooted about in my stash of cutters and found a 60 degree one which had flutes long enough to cut the angled ways in a single pass.

View attachment 343368

I turned up a 7/8" arbor for it and gave it a knurl so I could press the cutter on and off for the time being. Mounted it in a 1" long-reach collet which I put in the Clarkson T&C holder set at 35 degrees down angle. I dressed in a smallish wheel because anything bigger would foul the collet before cutting the whole flute. I used a hacksaw-blade stop on the gullet of the flutes to index the 20 flutes for cutting.

View attachment 343369

Once the flutes were all re-ground they had gained a very wide land on the primary cutting angle especially at the top where the most material had been ground off.

View attachment 343370

This is bad because if the primary relief is too wide the trailing edge of it will drag on the surface you just cut. I had never ground one of these types of cutter before and I was running out of time so I eyeballed the angle for a secondary relief to thin out the primary land.

View attachment 343371

It's done the job and ifI need to do more I will give it a lick with the mini grinder. So long as I keep away from the cutting edge it'll be fine.

Here's the cutter offered up to the job.

View attachment 343372

So hopefully I'm off to Andrew's tomorrow to stick it on his Bridgeport and straighten up these ways.

That's called getting it done ,hope this machine turns out as well as the work you've done on it Pete .

 

[Pete.]

That's called getting it done ,hope this machine turns out as well as the work you've done on it Pete .

Thanks Sean, I won't stop until I'm hppy with it

Had to change my plans today so no milling of ways. I will be doing it very soon though and in the meantime I have plenty of other things to get on with.

 

[Sean64]

Thanks Sean, I won't stop until I'm hppy with it

Had to change my plans today so no milling of ways. I will be doing it very soon though and in the meantime I have plenty of other things to get on with.

Going to be a helluva machine when finished ,what condition are the leadscrews and nuts in ?

 

[Pete.]

Going to be a helluva machine when finished ,what condition are the leadscrews and nuts in ?

The screws and nuts are very good, the main table screw is wick-fed oil from the pump reservoir.

I had an hour spare to do some checking of these two errant ways. What I wanted to find out is which one is in error and what the relationship is between them and the tee slots. The last thing you'd want to do is scrape or machine them straight and parallel only to find that the table slots aren't aligned with the direction of travel. That would make setting up the fixed table more tricky and put the zero-mark out on the tilting table and indexing attachment.

Anyway, I have my trusty surface gauge complete with sliding pins and this is the sort of job they are just made for. I stood the table inverted on a pair of timber bearers so I could get the suface gauge base on the table front and the dial gauge reached right over the top to take a reading off the angled ways.



Here you can see the hardened pins resting on the side of the tee slot. Luckily my tee slots are not chewed up or this would be difficult to do.



Measuring the bottom angled way at both ends and in the middle. As you can see we are at 0 - 1.5 thou - 0







Now the top tee slot. This is reading 0 - 1.5 thou - minus 1



So these readings concur exactly with the one taken in the video in post #404 which gave results of 0 - 3thou - minus 1 across the ways (the errors in these measurements added together) which is nice to see them agreeing, but more importantly I now know that if I set up the table for milling by indicating off the ends of the bottom ways I will be cutting my dovetails exactly parallel to the tee slots. I won't use the top ways as that will give me 1 thou runout which isn't a disaster but there's no point when the bottom ones are bang on.

Worth mentioning here that it is normal good form to use an original machined face for setting up to machine out wear - well, in this case just as with the column front the original bottom face of the table which is the face you can see in these pics and is nicely machined, is miles out. So far out that it sends my dial gauge right round full scale both ways until the stylus lifts off the face. So, you gotta be careful there and make several checks, never assume.

 

[Pete.]

I found a spare hour to re-do the reliefs on the dovetail cutter today because I was still worried that the lands might be wide enough to drag. I'm a lot happier with it now.



Checking the angle with my fish tail gauge, just because I had it. It's doubtful that it will match the console slide ways exactly but it'll be close enough to scrape in.

 

[Tigman]

Can you film the milling for us , I'm intrigued !

 

[j1312v]

I’ve modified dovetail cutter angles by grinding them in a spin fixture then manually relieved cutting edges with a die grinder. Cast iron isn’t too fussy
These days I’ve got the planer

View attachment 343254

Is that a Japanese copy of the old grindall?

 

[Pete.]

I bought a small 0.75kw VFD to run the high speed milling head, a great little bargain £40 from eBay. It should fit inside the RH cabinet I will run it up later and make sure it works, see where it will fit the best.