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IndustryArena Forum > MetalWorking Machines > Dyna Mechtronics > What BT30 pull studs does a DM2800 use?
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  1. #1
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    What BT30 pull studs does a DM2800 use?

    I've noticed that the handful of normal bt30 tooling with pull studs that I've collected hasn't been long enough to engage with the drawbar. Did dyna myte make its own proprietary pull studs or are these just really obscure obsolete ones used?

    So far I've collected about 20 nice tool holders, I'm hoping to find some cheapo Chinese pull studs so I don't have to spend another grand on tooling.

    Is there a pull stud model or critical dimensions I can search for on ebay to get some that work?

    Is it possible to change or modify the DM2800 draw bar to accept more commonly found pull studs?

  2. #2
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    Re: What BT30 pull studs does a DM2800 use?

    Yes.

    You'll always spend too much on tooling.

    I have attached the DM pull stud drawing for you.

    Timothy
    Dyna Mechtronics DM4400, Bridgeport Discovery 300, HAAS VF-0E, HAAS VF-2D
    BobCad 16, 20, 24 and now V25

  3. #3
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    Re: What BT30 pull studs does a DM2800 use?

    Quote Originally Posted by 2ferrous View Post
    Yes.

    You'll always spend too much on tooling.

    I have attached the DM pull stud drawing for you.

    Timothy
    Thanks 2ferrous! I actually sent you a message seeing if you still had a drawing before I saw this. The 45 degree inside taper defiantly makes more sense than the 30 degree taper I've seen.

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    Re: What BT30 pull studs does a DM2800 use?

    setlab,
    If you want to join me (and anyone else) we can make a bulk purchase and lower the price. Roland can supply them, but the more you buy, the better the discount, which is why I've been trying to hold off.

    I've considered making my own, but I have to admit that I'm a little worried about it. By the same token, if I have them coded up, then I can replace them more frequently..... The bigger issue is that I've been really challenged on getting good retention force from the Belleville washer stack. I suspect that if you measured yours, it wouldn't have as much strength as you might think, although the 2800 is a smaller machine than the 4400 (my thinking being that you probably are not as aggressive).

    Alan

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    Re: What BT30 pull studs does a DM2800 use?

    Quote Originally Posted by MrMetric View Post
    setlab,
    If you want to join me (and anyone else) we can make a bulk purchase and lower the price. Roland can supply them, but the more you buy, the better the discount, which is why I've been trying to hold off.

    I've considered making my own, but I have to admit that I'm a little worried about it. By the same token, if I have them coded up, then I can replace them more frequently..... The bigger issue is that I've been really challenged on getting good retention force from the Belleville washer stack. I suspect that if you measured yours, it wouldn't have as much strength as you might think, although the 2800 is a smaller machine than the 4400 (my thinking being that you probably are not as aggressive).

    Alan

    Id like to get all 20+ of my bt30 tool holders pull studs, that kind of depends on the individual price though. If you have a potential group buy I'm interested.

    If your washer stack isn't producing enough force try tightening the retention nut all the was down. Or measure how much room your washer stack area is and see if your missing any and can add more?

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    Re: What BT30 pull studs does a DM2800 use?

    OK, I'll find out how much they are. They are not cheap though... Sadly, the Dyna uses a custom retention knob.

    As for the stack... It isn't quite that easy. I've created a fairly elaborate spreadsheet, actually, to work out the optimum stack order, quantity, possible throw, etc.... But I have to measure how much power I can really get out of my piston. So far I haven't gotten it quite right. There is evidence of 'checking' on my spindle.

  7. #7
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    Re: What BT30 pull studs does a DM2800 use?

    As long as they also work with the 1007 im interested aswell. Depending on price naturally . Has anyone considered changing the draw bar to something more common like a Hass etc...... ?

  8. #8
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    Re: What BT30 pull studs does a DM2800 use?

    They are about $28 each, but it depends upon the quantity. As far as I know, but would confirm, Dyna used a single pull stud for their designs. And, yes, it is custom to their machines, which really sucks because they were never a giant manufacturer. As such, when they went bust, nobody continued producing the studs because it wasn't like a Haas where you'd sell 50K of them a year.

    I'm not sure how viable it would be to change just the drawbar. Internally, the spindle has to have a taper upon which the ball bearings (if you didn't know, this system uses a four ball bearings, not leaf grabbers) 'ride up' and grip the retention knob. You can't just change the position of that ramp, and that implicitly controls the timing and, therefore, height of the retention knob. Because all other knobs are shorter, you would need to lower the ramped area, which means adding a shim or some other material. It is an interesting idea though. I haven't really thought about it that much, but I'm pretty sure it would not be an easy change.

    The other option is to make the studs with a CNC lathe. Once you've programmed it, you should be able to make them pretty quickly. This is actually what one of the vendors told me would make the most sense. He said you really didn't need to harden them, although most of the commercial ones seem to be. Given how scary a broken stud can be, however, I think I'd substantially lower the time in use before I replaced the stud. But... it is an option. At some point, the only way we'll be able to buy these studs is to have 2000 made, and we won't be able to afford that.

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    Re: What BT30 pull studs does a DM2800 use?

    I think I remember 5 ball bearings. Here a schematic of what the internal spindle looks like for anyone thinking about building a new draw bar. It probably wouldn't be too difficult to do.

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    Re: What BT30 pull studs does a DM2800 use?

    Yeah, actually, I think you are correct there. I wasn't sure if it was 4 or 5, but it is still academic. You cannot just extend the drawbar, or make a new bearing holder. Both would achieve the same objective of lowering the bearings. But this likely mess up the timing. Either the cross holes will fall too low, allowing the bearings to escape, or the bearings will not be forced inwards, thereby capturing and securing the holder. The idea is sound, but I am pretty sure that you will need to modify the spindle too, and that gets to be quite a bit more work.

    The pivotal thing here, though, is what is the LONGEST knob you can find that is widely available. If it is fractionally smaller than the Dyna one, you might be able to get away with manufacturing a new rod or holder, thereby changing the required retention knob. But the Haas ones, as I recall, are quite a bit smaller.

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    Re: What BT30 pull studs does a DM2800 use?

    I just took a 2 second gander at the drawing from Timothy against a common BT30 knob. There is about a 4.5mm difference in height between the mounting face and the top of the 45 degree bevel which acts as the ball bearing face. That means to get that particular sample knob to work in our spindle, we need to lower to location of the ball bearings about 4.5mm. Frankly, my gut feeling is that this is quite a bit. I suspect that we'd drop the bearing out the backside of the nut. But.... It *is* an idea worth investigating....

    alan

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    Re: What BT30 pull studs does a DM2800 use?

    Has anyone considered using the 2800 or 1007 itself with lathe tooling to make the studs?

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    Re: What BT30 pull studs does a DM2800 use?

    Absolutely.... I referenced doing just that in one of my previous comments. This is what MariTool (think it was Mari) suggested I do. He said it wasn't all that hard and that it wasn't necessary to harden the part. The hardening only really helps alleviate all bearing indentation into the bevel area. The key here, however, is more fear, whether rational or not. I don't want a stud breaking, so I've been opting to go down the purchase route. However, at some point that will no longer be an option and some other approach will have to be taken. To me, making the part is probably more feasible than trying to adapt the spindle, but I think setlab's thoughts are worth investigating further. if the spindle doesn't have to be modified, then I'll probably go that route. However, 4.5mm is an awful lot to top the bearings. I have *very* strong suspicion that the bearings will no longer be captive if their location is dropped that much (remember, we are talking 4.5mm drop of the unclamp position too) and the ball bearings will just escape out of the back side of the holder. That would be a fatal flaw, and the only way to prevent this would be to somehow shim the ID of the spindle. At some point that gets to be so much work that you might as well just make the retention knobs.

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    Re: What BT30 pull studs does a DM2800 use?

    Geesh, I need to do a better job of reading looks like setlab already suggested changing the draw bar. Its a shame I have about 12studs but 50 holders I would be happy with 20 more but damn they are pricey. Seams to me there would be very little chance of breaking the non hardened studs. I would imagine that they are hardened to protect from outside wear. Stuff harden breaks way before tuff. They wouldn't be to difficult to case harden them.

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    Re: What BT30 pull studs does a DM2800 use?

    Quote Originally Posted by funford View Post
    Geesh, I need to do a better job of reading looks like setlab already suggested changing the draw bar. Its a shame I have about 12studs but 50 holders I would be happy with 20 more but damn they are pricey. Seams to me there would be very little chance of breaking the non hardened studs. I would imagine that they are hardened to protect from outside wear. Stuff harden breaks way before tuff. They wouldn't be to difficult to case harden them.
    Not something I feel like tinkering with but turning a slightly longer copy of the drawbar on a lathe and adding a small sleeve in the spindle to engage the ball bearings sooner for a shorter pull stud may work.

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    Re: What BT30 pull studs does a DM2800 use?

    LOL. Don't worry about it funford. I'm guilty of the same thing on a regular basis.

    They are, indeed, pricey, but not as bad as you might think. We have gotten used to $4 items from China. Well... everything is made in China now, but I guess I'm talking about the $4 items that were probably rejected from the manufacturer charging $30. The point is, it isn't hard to find retention knobs in the $30 range. Just look at MariTool or any of the other quality manufacturers of knobs (although, those *are* made in the US). I am sure that the ones that I was talking about bulk buying were probably made in Taiwan, likely in the same factory that produced them for Dyna when they were in business.

    Long term, I think that making our own is likely going to be the solution. I actually have that on my todo list as an experiment. And, yes, hardening them isn't going to make them less prone to break. Even the US manufacturer that told me I should make my own said that. It is about wear and that is all. But I'm a hobbyist. I don't use my machine that much. If I make 30 studs, they will last me a lifetime, even if I put a time limit on them of 100 hours (or whatever... literally just pulled that out of, well, you get the idea). The material just isn't that expensive either... So just replace them. And, let's face it, for those of us doing this as a hobby... It is just another thing to make!

    The ONLY thing that keeps me away from this is a concern that what I make might be somehow inferior to a commercial product. I do *not* want a stud to break on me.

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    Re: What BT30 pull studs does a DM2800 use?

    $27 ea and hundreds in stock ready to ship when I last ordered some from Retention Knob Supply about 12 months ago. You guys are crazy if you think it's worth the risk, time, and hassle of DIY'ing them when they're one phonecall away. Do you realistically need 20+ tools on a benchtop, manual tool change mill?

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    Quote Originally Posted by Sun God View Post
    $27 ea and hundreds in stock ready to ship when I last ordered some from Retention Knob Supply about 12 months ago. You guys are crazy if you think it's worth the risk, time, and hassle of DIY'ing them when they're one phonecall away. Do you realistically need 20+ tools on a benchtop, manual tool change mill?
    We need all the pull studs!.... For reasons

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    Re: What BT30 pull studs does a DM2800 use?

    Yes I'm definitely crazy. Do I need them? Probably not, I have ATC on my system but its probably going to be like the time I had to have a threading gearbox on my lathe and it took me an extra year to find one with it and I have used it less then 5 times.

  20. #20
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    Quote Originally Posted by Sun God View Post
    $27 ea and hundreds in stock ready to ship when I last ordered some from Retention Knob Supply about 12 months ago. You guys are crazy if you think it's worth the risk, time, and hassle of DIY'ing them when they're one phonecall away. Do you realistically need 20+ tools on a benchtop, manual tool change mill?
    If they are available then I’d never make them. So not crazy. It is interesting though. When I contacted RKS they said they didn’t have any! And that was at about the same time. Strange.

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