Zimmermann FZ-5

[Brian]

Is possible just to surface the panels in sections? If you are able to use battens to clamp sections flat to the bed you may be able to do just that. I hate having to readjust after each section, but if you leave enough to work out the inconsistencies with a handplane you might be just fine.

I think it the section being cut isnt clamped to a reference surface than this operation wont work out to a good result.

Havent had a moment to reply to the blog, but the T-sections look nice.

[Chris Hall]

Well Brian,

appreciate the input for sure.

The last round of making those longer inverted T-sections involved placing a pair of outboard support blocks (I used 3" x 12" parallels) on either side of the vise and then clamping. The vise's lower deck is 2.875" off the work table, so placing the stock on 3" blocks meant that the pieces were not sitting on the floor of the vise.

Since the Kurt vise exerts downward force as well as clamping force, I did not lock the pieces in overly tightly as I feared that might pull the middle of the stick downward. I took a pass or three down the stick, which, with 750mm of x travel, got me just over halfway along. Then I released the stick from the vise, spun it 180˚ and re-clamped. If the DRO was not in the way, I could have possibly used the rotary table function at this juncture. Then I re-milled the other end. The overlap zone revealed how congruent the cut surfaces were. in some cases, a heavier skim could cause the cutter to 'float' slightly high, so it seemed to be the best practice to take a final skim on the very light side.

I've been thinking about repeating the same process with the panels, but of course the issue of how to best support and clamp needs to be solved. The panels are a little longer than the inverted T beams, but not by much. I've been thinking about making a support deck of some sort to lay them on for milling. The trick would be in affixing a panel to the deck without distorting the panel. I wouldn't want a vacuum clamp for this reason, as it can easily distort the piece in sucking it down flat. I guess this problem also occurs with magnetic chucks/vices in metal machining, but at least there you could shim as required before activating the magnetic clamp.

It seems to me the best way to proceed would be to place the panel on a support deck, and fix it in some way so it is held but not distorted. I might be able to do that simply using countersunk screws at each corner, and shimming as required. Then I surface about half the panel, and then remove the support deck with panel still attached and rotate it 180˚. I would need a way of clamping and unclamping the deck to the work table, and thinking Destaco clamps would likely work quite well. Once both ends of a panel have been surfaced, the panel is removed from the support table and flipped over, and reattached. At that point, no shims will be required. I would then surface the other side, again from one end at a time, taking the board to a desired dimension. I would likely have to repeat the entire process at least twice, maybe 3 times, for each board, given the amount of stock to be removed.

I think it is possible that the middle of the board where the cut paths overlap might show some slight discrepancies in surface decking, however those issues are going to be on the order of 0.001"~0.003", so well within what can be cleaned off in final surfacing.

The ideal support deck here would be a sliding table on linear bearings, as that would eliminate any need to remove the support table and spin it around 180˚. I think that sort of set up might be something to shoot for eventually. Maybe in the shorter term if I could get a hinged support arm for the DRO, then I could make use of the rotary table function in some way. Again, though, this would be most ideal if the support table was a sliding mechanism.

[Brian]

My worry was that the panel might distort in the cut, which is why I am thinking it needs to be clamped to a reference plate. Maybe my worry is unfounded?

I think a sliding assembly could work nicely as well. An inner frame which supports the panel fully, sliding on rails which are affixed to the tabletop and clamped solid while cutting.

I saw those parallel bars.....whoa! Now those are reference material!

[Chris Hall]

Collets, collet chucks, tool holder types, taper standards -- - I had no idea this was so complicated!

It looks like the high speed spindle on my machine accepts Morse Taper 3 tooling and tool holders, however it is a proprietary type made by Zimmermann and no longer available, at least as far as I can tell. The regular types of Morse taper tools and tool holders will fit the taper no problem but cannot mount because of a thread difference. Consequently, I'm starting to look into getting a custom tool holder made. I have three tool holders presently, however one is a drill chuck. The other two accept a weird type of collet called 125E F-17 which are a specialty automated lathe collet and hard to obtain and only in metric sizes unless you get custom-made collets. So, at present, all I can use those tool holders for is to mount an 8mm router bit, which is not especially versatile.

And on the main spindle, I have ISO 40 taper tooling. Turns out there are tools with the same taper used in the US, designated as NMTB 40, BT 40, JIT40, and CAT 40. All have the identical 7/24 taper, however the detail differences mean they are not especially interchangeable with one another. The mounting is either by drawbar (where metric/inch differences arise between types) or by collet nut (where flange mounting differences arise). The flanges vary depending upon whether they are meant for an automated tool changer or not, and some have drive dog notches and some do not.

I've located some ISO 40 stuff in Germany by way of the web, but most of the time when I email the companies (in English) I do not get any response. C'mon, all they have to do is plug it into Google translate and they'd get a rough idea about the subject of my mails. I have sent messages using google translate, but it makes no difference.

I was getting some response from the TOS Kurim company in the Czech republic, however after I asked about electrical parts there has been total radio silence, despite sending three or four messages since. No idea why. It's irksome when you want to buy something and a company which has the products you need can't seem to reply.

Moderately frustrated but it will get sorted out eventually.