Is anyone using a Sputnik seat stay fixture on a bench mill (e.g. RF-30)?
I'm trying to figure out the best way to set mine up. The challenge is that even with 2" blocks underneath the tilt table I hit the handle for the Y-axis at about 50 degrees and and I'm quickly running out of space between the tubes and hole saw.
I asked Jeff if there are issues with running the fixture with dropouts up and he suggested that it's not optimal:
The issue with having the dropouts up is that you are trying to push the stays out of the jig and the large chip is being pushed into the stay. Also because I use a gantry over the blocks to push both of them down without any twisting force the gantry gets in the way of choking up as much as possible on the stay to keep everything as rigid as possible. Even without the gantry in the way cutting stays that direction is not as good as cutting them with the drops down, much more rigid and much less crashing or slipping.
I figure for it's worth trying this set-up to see how things go, but in case it doesn't work, I'd love to get some alternate solutions.
I have mine on a horizontal mill and on a rotary table so I may not be much help. Looking at the RF-30 mill online maybe rotate the jig 90 degrees and hang it over the side without the X handle center the y on frame center and adjust using the X? Or if it has two x handles remove one?
That's a good thought. I have some additional mounting hardware coming so that might be the ticket.
I saw a video of Firefly recently (Australia guy was visiting the shop) and saw the fixture on the horizontal mill. Am I correct in thinking that if you rotated your set-up 90-deg (to look like a vertical mill) you'd be milling with the drop outs above the cutter? If so, that might be a good indication that I could do the same.
I mounted the fixture on an angle table like this (https://www.grizzly.com/products/gri...10/g9303?gQT=1) and have it pushed to the left of the table as far as possible.
When I need some extra space I rotate the head of the RF-30 about 30-degrees (from 6:00 to 7:30) and it seems to work out OK.
I can't believe that I paid about $60 for that angle table back in 2018.
I mounted the fixture on an angle table like this (https://www.grizzly.com/products/gri...10/g9303?gQT=1) and have it pushed to the left of the table as far as possible.
When I need some extra space I rotate the head of the RF-30 about 30-degrees (from 6:00 to 7:30) and it seems to work out OK.
I can't believe that I paid about $60 for that angle table back in 2018.
I have my stay fixture vise all the way to the right, there is a block on the bottom of the SS fixture that clamps in the tilting vise so it gains some more elevation above the table this way, then I put a square block in the vise forward so the fixture is back toward you and this gives it more clearance as well, then I tilt it all the way up and miter the bottom angle if that makes any sense ?
- Garro.
Last edited by steve garro; 01-02-2025 at 11:09 AM.
So Steve, you like those extra-long holesaw arbors eh? Never tried one myself. Is it needed for this setup, to cut on the "short side" of the miter without running into the quill or the mill head? Maybe just for large frame size where the seatstay miter angle is small?
I use short arbors and fully choked-up against the collet, it does get a bit hard to see what I'm doing sometimes. Maybe I should try long arbors.
Ironically the LED ring light I added to the bottom of the quill takes up space and sometimes makes it hard to see. More light but no line-of-sight to the point where the magic is happening. So I just take the ring light off in those cases, 5 seconds with no tools required. I think a long arbor would mean never having to take the light off.
Here's a 60° DT miter setup (mocked up; that's really a seat tube in the pic). mitering plus 30°.jpg
I can reach, barely, with the short arbor in the pic, but a long arbor would help. Looks like it would be an absolute must for a real acute seatstay miter. I think I just talked myself into it.
I now have more long arbors and don't use the short ones nearly as often as the long ones. I had the same clearance limitations with the first short ones I got. Here's some of my set up, in this case the short arbor works... Andy.
So Steve, you like those extra-long holesaw arbors eh? Never tried one myself. Is it needed for this setup, to cut on the "short side" of the miter without running into the quill or the mill head?
I can reach, barely, with the short arbor in the pic, but a long arbor would help. Looks like it would be an absolute must for a real acute seatstay miter. I think I just talked myself into it.
My mill doesn't have enough vertical travel for a short one - this reaches and works well, it's done likely over 1000 stays in this mode = my CS fixture goes in the same vise but sideways to the cutter
- Garro.
Sorry for the wrong photo I just posted. meant to click on this one from a while ago. As many of the bikes I have made are small the SS/ST miter angle is large and the short arbor does just work. In time I got more longs and one by one transferred my cutters over. My mill is a, 8x30, about half the weight as a Bridgeport but still a knee type with a lot of vertical travel. Andy IMG_2013.jpg
Sorry for the wrong photo I just posted. meant to click on this one from a while ago. As many of the bikes I have made are small the SS/ST miter angle is large and the short arbor does just work. In time I got more longs and one by one transferred my cutters over. My mill is a, 8x30, about half the weight as a Bridgeport but still a knee type with a lot of vertical travel. Andy IMG_2013.jpg
There you go = I do the same, but in front of the foot that's bolted into the vise I have a block to take up the space, which moves the fixture rearward, allowing the vise to pivot more by opening up the arc between the stays & the head - make sense?
Jeff @ Sputnik gave a gentle warning that the SS won't be suported as well with the dropout end "in the air." Any thoughts on this?
in that instance, you're starting your cut where the tube has the most support both because of the "hang out" distance from the clamps and because the tube itself is still mostly intact and self-supporting on both sides of the cutting edge. As you finish the cut, the tube "hang out" is further from the clamp AND the whatever is left of the tube has lost a lot of its own rigidity so it's more likely to snag a tooth which can result in a broken tooth, a rotation of the tube in the clamp (and potentially more broken teeth) and a ruined cut.
I MOSTLY cut seat stays from the top and sometimes would even cut into the tube blocks on steeper stays. That said, the Sputnik fixture with it's round tube clamps on round tubes holds the tubes incredibly well and I don't recall a tube ever slipping in mine (unlike a fixture I had that used V blocks). If you're successfully cutting stays from the bottom, more power to you. You can give yourself better odds by making your own extended arbors in whatever the largest diameter your mill will accommodate. Even going from 7/8 to 1" helps on those longer arbors. My mill uses a BT40 interface so I made 1.25" arbors for all of my holesaws that had Weldon flats on them so I could use a Weldon holder with a set screw...both for rigidity and slightly faster changes.
FWIW, I have a 1.25" diameter arbor that has 10" of stickout that I used to miter the DO end of my "sweet stays" in a fixture that I made to cut both ends of the stays without removing them from the fixture. It was great for fat bikes with 197mm DO spacing and plenty stiff enough to do the job. I'm pretty sure the photo below is the "shorter" long arbor
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Sputnik Seat Stay Mitering Fixtures
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Originally Posted by false_aesthetic
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