Another Harrison Milling machine

[Fastdruid]

Changed my mind on how I was going to do this and ended up a bit compromised.

Originally I was going to drill and re-tap the base but then changed my mind and re-used the original holes. Trouble is though that these then exited in the raised "ring" section. So I had to counterbore them but as the milling machine is still in bits I and I don't have a suitable counterbore tool I had to do them using an end mill in the pillar drill. Now I'm fully aware that milling in a pillar drill is a big no-no as there is no retention of the chuck (beyond the morse taper) and it doesn't have the sideways stiffness to do it. I figured however that as I was "plunge milling" and hence no sideways action it would be ok. It wasn't. There was enough sideways deflection that it vibrated horribly and then dropped the chuck out. Managed it but ended up having to take it really really slow.

I also lined the oil port up nicely between two of the mounting bolts but didn't consider how it aligned the nut! I mean it doesn't matter but it would look neater if the flats were perpendicular to *one* of the axis (or even at 45°!)

It's functional however and not so bad that I feel I have to redo it!

 

[Fastdruid]

Cleaned up the Z ways a bit and then re-fitted the knee. Very very nearly forgot to fit the Y ballscrew which would have been beyond annoying.

It was a hefty old lump before, now with everything else added it's even worse!

With that in place I slowly lifted it up until I could fit the ballscrew in. I'm glad to say everything lined up perfectly.
I mean I know it _should_, I spent a lot of time measuring etc to ensure things lined up but even so it's gratifying when everything *actually* works as you expect.

The particularly good news at this point was that when I removed the straps I'd used to lift the knee and then disengaged the Z axis lock it *didn't* immediately dive for the ground. Seems that there is enough friction in the system to prevent that at this point. At the same time I could easily wind it up and down "by hand" which also bodes well.

Obviously this may not remain the case, there is a significant amount of additional weight to add but it's a good sign at least.

 

[Fastdruid]

One of the things I kind of forgot is that I need a sliding cover for the Y ballscrew. The original won't fit the new setup (the slot isn't wide enough) and would need a larger rectangular hole cut in it.

Partly because I'm trying to avoid hacking the original so much that it couldn't if desired be converted back to a manual mill and partly because it's already bent, scraped and damaged I'm somewhat loath to hack it about so it will need replacing.

Question to the masses is what should I get the new one made from? It's a simple 2.5" by 12.25" rectangle with a hole in the middle. I can't make up my mind if to go for just mild steel, aluminium or stainless. Each has their plusses and minuses.
Recommendations anyone?

 

[Mark Davison]

I made a new one from mild steel sheet. I was temped to use stainless as my original one was rusty (coolant under it), but the cast iron would still rust.

 

[Mark Davison]

If you are going to have to cut it around the nut carrier i suspect you'll end up with a gap at the front or back (i did)

 

[Fastdruid]

I made a new one from mild steel sheet. I was temped to use stainless as my original one was rusty (coolant under it), but the cast iron would still rust.

I wasn't entirely sure what the original was made from as there was *no* rust on mine and I thought it should have rusted if it was mild!

Must have just been lucky, I don't think there's been much coolant used on this one.

 

[Fastdruid]

If you are going to have to cut it around the nut carrier i suspect you'll end up with a gap at the front or back (i did)

Its not a problem, I've a plan to protect the ways anyway. I'm fed up of clearing chips off them and that's only ever going to be more of a problem when it's fully CNC.

 

[Fastdruid]

Tiny bit of slowgress. I turned up some plugs for the oil ports, drilled and then tapped M6 before stuck in the freezer and then tapped in with some sealant round them. Think they should come out if I ever want them to with little more than an M6 bolt tightened in but they're aluminium anyway so should be relatively simple to remove.

The observant may notice an extra hole (on both the picture above and below) that wasn't here before and that this port in the photo below is extended out slightly. We'll come to why later...

The oiling ports on the top swivel section I've decided I'll feed from the back. They're not M6 but rather 1/4" however given that it only needs a couple of threads an M6 thread "works" well enough. I've done the same on the sides of the knee.

 

[Fastdruid]

On an unrelated note to the CNC conversion it turns out that I need a new Horizontal Arbor. Not that I've ever actually used it as a Horizontal milling machine so I guess there is no real rush however I was cleaning up the one and only one I have that came with it and realised that someone had turned a 1 1/4" arbor down to 1"...except for about a 4" section.

But then it had 27mm spacers with it rather than 1". So I don't have the correct spacers and I don't have the correct arbor for _anything_.

 

[Carl Wilson]

Do you have the support for the arbour with the needle roller bearing in it? I have the support but it is missing the bearing.

 

[Fastdruid]

Do you have the support for the arbour with the needle roller bearing in it? I have the support but it is missing the bearing.

Yep, complete with bearing. It was of course like everything else filled with grease and took some cleaning out but I have it. The end section for the arbor is at least correct so I have one for a 1" arbor at least.

 

[Fastdruid]

Been busy with a load of boring wiring, setting things up etc.

Bit of good news bad news.

Good news first. After a few false starts I've had a motor turning via the "computer".

Bad news; I didn't buy all of the drivers at exactly the same time. One of them is more "advanced" and has a small 4-char LED display.

Unfortunately it appears that one is a bit too sensitive to the ramp up in power from the slow starter on the radial transformer (which is there to reduce the inrush current and hence allow sensible sized MCB's/not blow the MCB 50% of the time) and throws an Er01 which is "over-current" (or to put that another way, not _enough_ current in)...and then once you reset the error (after the slow starter has done its thing) is fine. Equally if I plug it in after the power has settled its fine.

Reading the manual I think I can reset it by using the "Enable" signal or I can set things up so it uses a(nother) relay and power it up when the voltage has settled.

Need to have a bit of a think which way to go here.

 

[Fastdruid]

Another thrilling instalment!

But seriously this is a pretty major milestone. First axis to actually move under it's own power controlled from the computer.

Perfectly happy to hold itself up and ran up and down as smooth as you like (I have some more video which is just of "jogging" it up and down). Speed limits and acceleration limits currently are right the way down. I bench tested the motors and it felt a little too aggressive to jump in with that. Particularly as I have no limit switches fitted let alone setup!

 

[Fastdruid]

Next axis working under CNC control.

Still a mile away from cutting metal but getting closer.

Can't do X yet, both because I've not worked out the cable routing and also because I realised I'd used the same belt size twice and as I'd only ever put things together one axis at a time I'd missed it. Ordered a new one so should be able to assemble that in a few days (by which time I'll hopefully have worked out the cable routing too!

 

[Carl Wilson]

Brilliant progress.

 

[Fastdruid]

I'd originally planned on binning the lamp that had come with it. On further investigation I realised it was a BHI Lo-Vo Lite and actually quite a decent thing so I decided to re-use it. Albeit not with the original transformer, I'll either run it as a 240v lamp or convert to something LED.

As I'm awaiting parts I started to clean it up as it was utterly disgusting. It was brown when it _should_ have been grey (and originally black before I presume Harrison painted it).

This is what I started with. Note the colour on the aluminium "cup"...

After some _serious_ cleaning. To put that into some context, I didn't even know there *was* that sticker on the back until last night!

A before and after of the covers for the first "elbow". I'm not going to bother to make it utterly mint, respray everything etc, just want rid of the 55 years worth of ingrained dirt!

Oh and on a related note I discovered when I took it off that Harrison had drilled/tapped through into the gearbox to mount it and if you left it off it would dribble oil out of the screw holes!

 

[Carl Wilson]

Great job with the parts of the light. I have the same one. What did you use to clean it?

 

[Fastdruid]

Great job with the parts of the light. I have the same one. What did you use to clean it?

Elbow grease (the product) and elbow grease.

Not sure it was the best thing though, took a lot of effort but I'm not sure if that would have been the same regardless. I did consider if using something "oily" like paraffin or WD40 would have stripped it off easier (and then degrease).

 

[Mark Davison]

Likewise, same lamp on mine. I've converted it to take a standard GU10 LED spot bulb.

 

[Mark Davison]

Fit the limit switches before you go much further, you'll regret it if you don't. I ran mine to the end despite trying to be careful!