Another thinking-out-loud about Rose Index

[tjb]

I found epanzella's recent thread on a Rose Index to be very interesting:

Rose Index Question

It's raining so my outdoor projects are squashed for today. Rather than watch Opra I decided to knock out a Rose index. I just sliced off a 4" x 1" hunk of steel with my bandsaw but before I start making chips I have a question. What is the purpose of having both a 4 sided and an 8 sided section...

www.hobby-machinist.com

For quite a while now, I have been thinking about making one for myself, and it looks like enough free time for this project is right around the corner. A question has occurred to me. Is there any significant reason, other than efficient use of material, to fabricate a single plate for the three major configurations (4, 6 and 8 sides)? It seems to me theoretically, that rigidity would be optimized if there were a single indexing plate for each configuration. I ask this because I've been sorting through my scrap aluminum bin, and I can do it either way. I have quite a bit of 4" x 3/4" aluminum from which I can make individual plates, and I also have a piece of 1-1/4" thick stock with a usable diameter of about 6-1/4" from which I could make a single plate in the conventional fashion.

Would very much like to hear some opinions before I begin butchering some metal.

Regards,
Terry

 

[tonydi]

I'm not sure about need for extra rigidity since you're only going to put a square up to the sides, it's not like you're putting any loads on it.

I made mine out of 1 piece of 2.5" OD aluminum rod, 1.25" in length. I made one face into the hex and the other the octagon. I opted the just do the two, not seeing the reasoning for making a square when I've already got that capability with the octagon. I left an uncut section in the middle to locate the SHCS for locking the rose in place.

Since I don't have any equipment to rotate the piece exactly I came up the idea to use my electronic angle box. I knew the first cut would be square so that I just needed to accurately (well, as accurately as I could given the circumstances) rotate that cut to 45 or 60 deg and make the next cut. I tried to keep the angle to within +/- .05 deg. When it was done I could take my protractor tool and visually it sat flush against all sides so I think it was close enough for govt work.

I forgot about taking pictures as I did it but I just took a couple to show what I did.

 

[epanzella]

I clocked two sides of my octagon parallel with two sides of my hexagon. I'm putting the set screw in that spot so I can hold my square on either the hex or the octagon to work around the setscrew if it's sticking out.

 

[tonydi]

Yep, same here. I machined the hex first and then made the first cut for the octagon with the hex clocked to the same position.

It's funny, I'd seen this rose index idea when Mr Pete had a video about it some time ago and it looked cool but I forgot about it afterwards. Then I made my hex wheel center caps and could have used a rose index. Then the threads started here and I just got caught up in it and decided to make one since I already had the stock from the wheel cap project. Heh, I'll probably never need to actually use it but hey, that's probably the case for a lot of the tools I've made since getting a lathe and mill.

 

[Weldingrod1]

Of you want to generate the angles you could drill a set of holes with the right coordinates to hang your part on pairs of dowel pins, then clamp it...

Sent from my SM-G892A using Tapatalk

 

[tjb]

I'm not sure about need for extra rigidity since you're only going to put a square up to the sides,

Yeah, I agree. As I noted added rigidity is only 'theoretically' optimized. Another applicable adverb might be 'negligibly'. I like the device you made. I have about a two foot section of 3" square aluminum, so I could do essentially the same thing, but I sure do hate to cut up that piece. The separate plates approach appeals to me because it is the most dispensable aluminum stock that I have. With regard to a compact index or individual pieces, I suppose I'm of the opinion there's not a particular advantage either way - 'theoretically' speaking, of course.

Great comments from everyone. Any others have pictures or ideas?

Regards

 

[DiscoDan]

The December / January copy of Machinist's Workshop magazine has an article on making a rose index