timo888 wrote:The thread is M12x1.75 to be compatible with standard handles?

You are correct, for the Cremina's handles. It may be whatever a customer requires.
Cheers
richard

I have talked with Lino... Lino is willing to make a batch of bottomless portafilters for the Cremina out of stainless steel. Would anyone else be interested in this venture? I would be sending him mine as a prototype to go by.
Lino can be contacted at: lino@vernadesign.com

49mm? So they woulld fit Maximatics and older Liviettas? I smell an opportunity!
paul

Hey Guys,

I figure it's time for me to chime in...

Before I get started making too many PFs of different sizes and types, let me slow things down a little...

I'm going to *try* to make a PF for the Cremina. Do they vary by year like the Pavoni? Or is there only one size?

The hardest part of making a PF (if you aren't casting it) is to cut the helix in the PF ears. That helix isn't shown on the drawing above, but I assume that there is one. If the PF was made from stainless and without that "ramp" you'll get contact only at a very small point when you lock in. That will lead to pretty rapid wear at that spot. And it will be the brass grouphead, not the PF that gets worn.

This probably won't be a fast project, as most of my "extra" projects aren't (Dan can attest!), but feel free to ping me on this thread or by email if you want an update.
My CNC machine isn't operational yet, and this job requires it, so that's another slowdown.

I've got pretty much no idea of cost right now, except that it will likely be on the far side of $100.


Hopefully I'll have more to add later.

ciao

lino

lino wrote:The hardest part of making a PF (if you aren't casting it) is to cut the helix in the PF ears. That helix isn't shown on the drawing above, but I assume that there is one.

The slots in the group are ramped; the ears are as Richard drew them, though I think the leading ear-corner is a smidgen less abrupt, i.e. slightly greater radius, and the bottom is not perfectly flat, but has a slight arc.



Regards
Timo

lino wrote:Hey Guys,

I figure it's time for me to chime in...snip

Before I get started making too many PFs of different sizes and types, let me slow things down a little...

I'm going to *try* to make a PF for the Cremina. Do they vary by year like the Pavoni? Or is there only one size?

The hardest part of making a PF (if you aren't casting it) is to cut the helix in the PF ears. That helix isn't shown on the drawing above, but I assume that there is one.

Hi Lino,
The ears on my Cremina have about a 6" radius not a helix on the bottom. Should you wish it, I shall send a DXF of the drawing to you. Send a PM to me. I just got the Bronze to try one of the above for myself. Bottomless with a brazed handle shank is no problem on my lathe and baby mill., CNC might be needed for a full PF. However, a shaped spade bit would do the inside job. and inside jaws + a template and file would do the outside.

My CNC machine isn't operational yet, and this job requires it, so that's another slowdown.
I've got pretty much no idea of cost right now, except that it will likely be on the far side of $100.

That's about the price point I was coming from doing a few at home.. I took the drawing to a shop and they were in the $200 each for a lot of ten. The shops around here start at $65 per hour simple and expect $150+ for CNC time. I'm sorry that I wasn't aware that you didn't have CNC when I suggested contacting you. Your photos show such awesome construction and finish.

Hopefully I'll have more to add later.
ciao
lino

Thanks for chiming in!
sincerely
richard / espressme[/quote]

On the choice of material...

The Oly Club manual recommends running the PF under cold water between shots to keep the Club's group from overheating. To that end, could the naked PF be made from brass instead of stainless? Less wear and tear on the group slots too.

Regards
Timo

timo888 wrote:On the choice of material...

The Oly Club manual recommends running the PF under cold water between shots to keep the Club's group from overheating. To that end, could the naked PF be made from brass instead of stainless? Less wear and tear on the group slots too.

Regards
Timo

Brass would certainly be easier to machine. It looks like material would cost between 50 and 75% more for brass. Though that depends largely on the alloy of both the brass and the stainless.

I'm not sure I can polish brass and I'm quite sure I can't chrome it, so, from me, you'd be left with bare brass.
Stainless I can polish, so it'd look better.

Bob wanted stainless, so that's where I'll start.



It's great to hear that there is no ramp in the ears. That moves the job back into manual machine territory, though the ear profile will have to be hand finished.

Hmmm.... The little wheels are turning.

Hey Richard, thanks for the DXF offer. I think I'll take you up on it, even though I'm getting a PF to hold in my hand and measure too.
For what it's worth, here's the business side of My Shop:

The "Santec" pictured at the bottom, outside, early during disassembly, was, isn't now, but will besoon, a CNC machine. My Bridgeport looked much worse than that when I first got it home...
Also, all the bottomless PFs I cut are done inside the Tupperware (that everyone asks about) that's sitting on the rotary table. It contains the chips.

ciao

lino

lino wrote: ... PF for the Cremina. Do they vary by year like the Pavoni? Or is there only one size?

There are some changes in baskets which lead me to believe that there may be some variation in the PFs, perhaps in the basket-rim-support-wall and in the contour where the cup base transitions to the inner wall. Only the former variation, if it occurred, would be relevant for a naked portafilter.

My Cremina was made in 1992. (Club made in the mid 1970s-- differences noted, if any)

I.D. 51.2mm (Club: 52mm)
Basket-rim support wall height ?.?mm (Club ?.?mm )
O.D. above the ledge at the rim-support 54.4mm
O.D. below the ledge 56.5mm
Ledge breadth: ~1.05 mm
O.D. at the ears 62.5mm (Club: 62.9mm)
ear-length 20mm
ear max thickness 4.4mm
top of ear flush with ledge

Thread M12; 1.75 pitch




Regards
Timo

Sorry if I confused the issue talking about 49mm. That was what I thought the earlier PFs were (cremina67) and that is what is used in the earlier pump driven Olys also. Thought that a larger market for these might be beneficial, but if not.......

Anyway, my ignorance was showing and I apologize.
paul