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  1. #21
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    Default Re: fretting on 30 taper tooling

    Martin,

    Since my spindle was purchased from a salvage dealer, I do not know what year machine it came from. The dealer says it was from a Dyna Mechtronics 4400 and I didn't think to inquire about the serial number of the machine, if he still had it. So, I can’t say for certain that my design will match yours, but it does match the cross sectional drawing that we've been referring to.

    The reason I took mine apart was because my clamping force was getting less and less. It turns out that my assembly was missing Item 22. This was allowing Item 20 to loosen. For my drawbar, Item 22 is an M5 x .5 Screw, even though the drawing says M10x10. I got a new screw and made a small brass washer to go under the head. Otherwise it would not shoulder out on item 20, and keep it from loosening up. Maybe the original screw was a special screw with a large diameter head, like a pan head? I guess the slot you are seeing could be the head of this screw??

    In the attached pics, I laid out the drawbar assembly (forgot to show the balls). As the drawing shows, there is a small grub screw down by the Stud Chuck(15), but there is not grub screw at the top. It is not necessary to remove this screw unless you need to remove the Stud Chuck. I also attached a pic of the tooling I used to get it all apart. My Stud Chuck tool looks just the one show by Caprirs, I had to make mine a little bit smaller to fit inside the balls. I turned the top with a ¾ wrench.

    My assembly only had 78 springs, so maybe the previous owner had removed a couple that broke? The arrangement is (((()))) repeated 10 times. Please let me know if this matches yours.

    I think your advice on the opening the spindle up is good. Since it runs quiet and true, I will not disturb it.
    Thanks,
    Walt
    fretting on 30 taper tooling-assy-jpg
    fretting on 30 taper tooling-tools-jpg
    fretting on 30 taper tooling-tool-jpg



  2. #22
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    Default Re: fretting on 30 taper tooling

    Walt,
    Thank you for your excellent work. Is item 20 shown as the third from the left in your pic a single thing rather than made from two or three bits (aside from the O rings of course)?
    I think that my spindle design might be a bit different. In the next few days I will photograph the top down view of my spindle that you get when the pressing bar mechanism is removed. I suspect that it will be quite different from yours.
    Martin
    Old foundry men never die their metal just goes out of spec.



  3. #23
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    Default Re: fretting on 30 taper tooling

    Walt,
    I managed to get at my Dyna and remove the pressing bar mechanism, the attached pics show what the top of my spindle looks like. Item 20 and the O ring that sits in the top of it are clearly visible but my central bolt (#22 I guess) clearly has a screwdriver slot in it. The small grub screw in this slot is clearly visible. It is this grub screw that refuses to undo! Looking at the slight brown translucent substance around the grub screw I would guess that it has been Loctited in. This substance is sort of hard and brittle - I managed to chip some of it away as is evident in two of the pics. I guess that I will have to try applying a bit of heat via a soldering iron to soften the Loctite and then try undoing the grubscrew. Unfortunately it looks as though the Loctite may have also been used on the slotted screw, this could prove to be a worry! My guess is that the grubscrew is a locking device to hold the slotted screw in place that stops #20 from coming loose. So we would seem to have a Loctite locked locking device that locks the screw that locks #20 - Ah yes the old belt and bracers approach methinks.
    If anyone out there can shed a little light it would be very much appreciated.

    Martin
    Old foundry men never die their cores just blow

    Attached Thumbnails Attached Thumbnails fretting on 30 taper tooling-dscn0523-jpg   fretting on 30 taper tooling-dscn0517-761x800-jpg   fretting on 30 taper tooling-dscn0513-800x793-jpg   fretting on 30 taper tooling-dscn0522-jpg  



  4. #24
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    Default Re: fretting on 30 taper tooling

    Martin,

    I think your's is the same as mine. Is it possible that someone replaced the screw on yours (mine was missing) with a custom design, and added the grub to lock it? I wonder if you could make a slotted tool that goes over the grub and allows you to torque the slotted screw? If so, I might unscrew. I'm a mechanical engineer, and I've never seen a design that uses a little screw like this, I'm guessing it was added by someone.

    The dimensions of my Guide(20) are 22mm OD x 39.3mm long with a 10.2mm dia hole for the screw. You can see in the pics the radial holes for the air-blow. On the inside, it makes sense to keep the thickness of the screw head as low as possible, to keep from covering up the airports. This might explain the slotted head design because it is has a low head height. My brass washer and M5 screw partially cover the ports, but I think the air will still find its way through. You should be able to see these ports by looking down through the top. For reference, the drawbar is 10mm dia.

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  5. #25
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    Default Re: fretting on 30 taper tooling

    Correction - Upon closer inspection my Belleville washers are stacked as (()) repeated 20 times for a total of 80 springs. I'm ordering McMaster Part# 96445K247 to replace mine. Does anyone have the software to calculate the spring rate and total deflection of this stack?

    Thanks,
    Walt



  6. #26
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    Default Re: fretting on 30 taper tooling

    Walt,
    Am exhausted from making castings all day so will reply in more detail tomorrow (or maybe the next day as I have to cast tomorrow too) but for now try
    Disc Springs to DIN 2093
    You will need to know what the total deflection is when the tool is released and then you will have some calculations to do but you engineers were always pretty good with a slide rule so it should be no problems. Just make sure that McMaster part is 10*20*1 i.e. that it is actually a metric washer. If it isn't I would be looking to get the correct size from somewhere in Europe or UK
    Again thanks for your photos and effort etc. it is much appreciated.

    Martin.
    Old foundry men never die they just miss-run



  7. #27
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    Default Re: fretting on 30 taper tooling

    hi
    I am searching to find data for draw bar force calculating :I find this technical data in PDF format ;

    http://tacrockford.com/pdf/100.311/1...ing-forces.pdf

    in this technical data " Steep Taper30 is 1200 lb-fr or 5340N"
    for < D201021 Belleville washer 20*10*1>mentioned force is 1450 N at each washer ;so we achieve 3*1450=4350

    even if we use stacked washer as ((())) repeated is not enough because <3*1450=4350>
    I don't understand how can I use with stacked washers as (()) while they create 2800N force in draw bar



  8. #28
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    Default Re: fretting on 30 taper tooling

    I'm not sure how to make the calculation, I guess it depends on the deflection your drawbar needs to release the pullstud. I just put new McMaster springs in mine and I know empirically that it takes about 1900lbf to compress the stack far enough for my tool to fall out. I know this based on the air pressure acting on my (2) 4.5" dia pistons. However, after the tool is pulled up into the taper, there is only about .150" of spring compression acting on the pullstud.

    Walt



  9. #29
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    Default Re: fretting on 30 taper tooling

    Well I finally bit the bullet and pulled the Bellville washers from my spindle. It’s clear that there are at least two different designs of the spindle in this area. XWalt’s #20 has a left hand internal thread, mine was most definitely a right hand thread 10MM *1.5 pitch. There was no sign in my design of the 5 *0.5 screw that X Walt found. Instead mine had a 10*10 grubscrew (slotted not hex keyed) and looks exactly like the spindle assy drg in the manual. The design appears to be such that one first screws #20 onto #14 and then screws #22 down inside #20 (the thread in #20 is long enough to allow this) until it locks against the top of #14, thus preventing everything coming undone in service.
    In my case an act of some butchery had been performed when presumably the washers were replaced on an earlier occasion by butchers unknown. A rough groove had been hacked in the top of #14 and #22 had been drilled off centre and tapped to take a long 10*32 UNF grubscrew. Presumably the idea was that after #22 was screwed in place (inside #20) the 10*32 grubscrew would be screwed down through #22 and into the crude slot in #14. I guess that this was to act as some sort of double belt and braces locking device to prevent #20 coming undone in service. To make really sure and put on another “belt” #22 and the 10*32 screw and the inside of #20 were plastered with araldite. As it happened the 10*32 grubscrew missed going into the slot striking the top of #14 partly to the side of the slot so the hope for locking mechanism did not come into play and even worse #22 did not bottom out on the top of #14. I guess it was all held together by the araldite. Photos below should make all this a bit clearer.
    I will be using a new 10*10 grubscrew bolted down against the top of #14 (with the crappy hacked slot cleaned off) just as the manual shows when I do the reinstall. I will not use anything like the 10*32 arrangement or even Xwalt’s 5*0.5
    But there is a problem. All my Belvilles appeared to be in good condition (I will fit new ones anyway) and they were arranged as Xwalt found and as indicated in the manual. i.e. 20 groups of 4 washers each arranged (()) yet I suffered bad fretting when using the side of a end mill - the spindle seemed to rattle badly, there was severe chatter, and the taper showed typical fretting rust if the load was heavy. As mreza points out (message #27) the recommended pull force for a BT30 is 5340N or about 1200 Lb force unfortunately the force exerted by a SINGLE 10.2*20*1 bellvile washer at say 45% deflection is just 922N, stacked 2*2 as indicated above gives us about 1840N. In theory this is nowhere near enough to hold the tooling properly and fretting chatter etc would rightly be expected. My washer stack certainly came out as a 20 *(()) just as Xwalt’s photo shows that his did too. The manual shows this arrangement too but the various manuals are so full of errors that I don’t trust them. So can anyone out there who has been down this road confirm the arrangement that they found. An alternative that I may well adopt is to fit the washers in 10 groups of 8 (((()))) essentially this will double the load to 3700N still short of the 5340N recommended but it just has to be way better. (At 75% deflection this arrangement will give 5300N) However my alternative will only have half the possible movement range of the arrangement that I found – will this be enough I wonder? It also of course may well overload the pressing motor. I would greatly value your thoughts and further information.
    Martin

    Old foundry men never die but Boy do they get old and tired

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    fretting on 30 taper tooling-dscn1074-800x600-jpg



  10. #30
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    Default Re: fretting on 30 taper tooling

    Whilst sitting in front of the TV I realised that the only possible arrangement of 80 washers is indeed the 20 groups of 4 (()) etc. The length of the washer stack varies considerably if another arrangement is used. As each washer is 1 mm thick and has a cone height of 0.55 mm the 20 groups of 4 have a length, or should I say height, of 80*1 plus 19*1.1 (for the 19 “gaps” between the 20 stacks plus 2* 0.55 for the “half” gap at each end giving a total of 102 mm. looking at the idea of using 10 groups of 8 (((()))) we have 80*1 plus 9 * 1.1 plus 2*0.55 - a height of just 91 mm – 11 mm too short! We could of course add an eleventh group of eight taking us to a total of 88 washers and giving us a height of 100.1 mm - a flat spacer of 1.9 thickness would finish the job. However measurements taken today show that this idea is a non starter.
    The 20 groups of 4 have a possible movement to full deflection of 22 mm whereas the 11 groups of 8 have just 12.1 mm. On assembly the washer stack height is compressed by 8mm and is thus preloaded. This represents the tool clamped but NO tool in the spindle position. i.e. #14 is pulled up so that #15 is hard up against the internal step in #1. To unclamp a tool #14 etc are pushed down about 9.5 mm from this position, when a tool is present and clamped the position is about 5mm higher than this. Thus including the initial preloading the washer stack must be capable of compressing at least (about) 17.5 mm. The 11 groups of 8 just do not have enough movement. The one that might be a goer though is 14 stacks of 6 ((())) this gives a height of 99.4 and a possible movement of 15.4, now by dropping the initial preload distance to 5.4 (the actual preload is still higher than with the 8 mm and 20 stacks of 4) we have a movement of 10 mm available in addition to the preload but we only need about 9.5. Load at tool clamp will go from 2360 N to 3838 N a 50 % improvement maybe this is what I will try! (After I first check that the problem is not that my existing washers are just weak – they sure look OK but a test is in order me thinks.
    PS. My thanks to Caprirs for providing the info re the tools necessary to get the washer stack out. I now have my own set!
    Martin.
    Old foundry men never die they just chill out



  11. #31

    Default Re: fretting on 30 taper tooling

    Sorry for bringing up an old post, but i have a DM4400 that is going to be retrofitted. I have removed the mounting plate and the SEM spindle motor. I discovered that when the machine have been sitting over night I can't spin the spindle freely without turning it 1/8 turn CW and CCW a couple of times. And when it loosens up it sounds like there is some bad things going on with the angular contact ball bearings. I think they are shot and needs to be replaced.
    Any input from you dynamyte veterans ?



  12. #32
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    Default Re: fretting on 30 taper tooling

    Quote Originally Posted by oscilloman View Post
    Sorry for bringing up an old post, but i have a DM4400 that is going to be retrofitted. I have removed the mounting plate and the SEM spindle motor. I discovered that when the machine have been sitting over night I can't spin the spindle freely without turning it 1/8 turn CW and CCW a couple of times. And when it loosens up it sounds like there is some bad things going on with the angular contact ball bearings. I think they are shot and needs to be replaced.
    Any input from you dynamyte veterans ?
    You probably should start a new thread.

    If your spindle is not connected to the motor and rough to turn, then it does sound like you have bad spindle bearings. Suggestion you post a new thread, Dyna DM4400 spindle bearing trouble....I have never had mine apart, but I understand there is some special tooling or process to take it apart.

    Marty



  13. #33

    Default Re: fretting on 30 taper tooling

    Thanks Marty, I have made a new post.

    -Mathias



  14. #34
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    Default Re: Fretting

    I have been holding off on doing milling on my machine until I've fixed my "to do" list. One of these was a "check" item, namely the retention knob pull force. I was going to make a gauge but then one popped up on fleaBay for a reasonable price (Clamprite). I bought it and, well, I'm glad I did. I am only showing 100PSI which is insanely low. I was stunned and more than a little disheartened. But, I'm also glad to have found this before I do much work. The previous owner had only used the machine for one job that came in periodically over multiple years. A brother took over the business and didn't want to learn the Mitsubishi control, which is how I got the machine. When I first looked at it, a holder was in the spindle. I don't know how long it was there, but I'm guessing a long time. The job they were doing used a teeeeny little endmill, so I'm guessing there was very little load on it. The taper looks fine and I don't see any fretting. That low load probably saved the machine's bacon.

    Anyhow, the point here is that it looks like I'm going to be resurrecting this thread and, hopefully, adding some photos. I know that the previous owner replaced Belleville washers at least once because I found some notes (the McMaster Carr P/N, for instance) in some notes he had. I also found the bottom half of the "special" tool rolling around in the back by the electrical stuff (always check before plugging in after a move!). The top tool doesn't seem to be anywhere, although I'm kind of wondering if it is necessary. It looks pretty easy to make if I need it, though. Oh, the bottom tool was made of aluminum, but the consensus here seems to be that this will be OK. The whole process of taking the drawbar out is a bit difficult for me to visualize, but I haven't spent much time yet on it. I should look before I ask questions there.



  15. #35
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    Default

    Have you reached out to Robert? He may have a procedure which might make it easier for you.

    Also it would be interesting to see what the clamping force my machine has. I know it's a different machine but still.

    Quote Originally Posted by MrMetric View Post
    I have been holding off on doing milling on my machine until I've fixed my "to do" list. One of these was a "check" item, namely the retention knob pull force. I was going to make a gauge but then one popped up on fleaBay for a reasonable price (Clamprite). I bought it and, well, I'm glad I did. I am only showing 100PSI which is insanely low. I was stunned and more than a little disheartened. But, I'm also glad to have found this before I do much work. The previous owner had only used the machine for one job that came in periodically over multiple years. A brother took over the business and didn't want to learn the Mitsubishi control, which is how I got the machine. When I first looked at it, a holder was in the spindle. I don't know how long it was there, but I'm guessing a long time. The job they were doing used a teeeeny little endmill, so I'm guessing there was very little load on it. The taper looks fine and I don't see any fretting. That low load probably saved the machine's bacon.

    Anyhow, the point here is that it looks like I'm going to be resurrecting this thread and, hopefully, adding some photos. I know that the previous owner replaced Belleville washers at least once because I found some notes (the McMaster Carr P/N, for instance) in some notes he had. I also found the bottom half of the "special" tool rolling around in the back by the electrical stuff (always check before plugging in after a move!). The top tool doesn't seem to be anywhere, although I'm kind of wondering if it is necessary. It looks pretty easy to make if I need it, though. Oh, the bottom tool was made of aluminum, but the consensus here seems to be that this will be OK. The whole process of taking the drawbar out is a bit difficult for me to visualize, but I haven't spent much time yet on it. I should look before I ask questions there.




  16. #36
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    Default Re: fretting on 30 taper tooling

    Roberto... LOL... He is super helpful but I bug him on a regular basis so I don't want to overload him. I try to "self-help" as much as I can and then ask him in the event I run into an issue. I'm not quite at that point yet because there are others here that probably have the answers. If I run into something we can't figure out, then I'll certainly contact him. Let me put it this way. He is a super resource that is willing to help people out. I don't want to abuse that.

    I've got an ongoing conversation with 2ferrous about some things, including the Belleville washers. He said that his hold pressure probably wasn't too far off from my measured 100PSI. If you read through this thread, he pulled a holder out of the machine (well, that was a programming error, but it identified the problem with the strength of the washers). So, I guess my measurements might not be garbage. I was actually thinking of sending the Clamprite back to the manufacturer for validation. They will do this for free if you pay the shipping. If you want a NIST cert then it costs, but I'm a home shop guy; I don't care about NIST, but it would be nice to know if the gauge is correct. I'm thinking that it probably is though. The design is elegantly simple so as long as there is no air in the piston, it should measure the force accurately. BUT, there is some question there. I've got some oil around the gauge (can't identify where). Given that the only thing with oil is the piston, it might well be that the unit has a bad o-ring and is leaking. This is all just a trace amount, though, so I'm not willing to say there is an issue with the gauge. I must say that I'm happy with its purchase though. I think that if it is correct, the gauge has paid for itself. I may still make my own and sell the one I have eventually, but that is project #100.

    Jay... If I remember correctly, you are in Morgan Hill and got the DM1002. If so, we can check yours sometime.



  17. #37
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    Default Re: fretting on 30 taper tooling

    Like all compression springs the more you expand them from the compressed state the less pressure you end with....this would apply to all Bellville washers too but more so as they flex very little.

    A typical pull stud clamp only needs to move down about 5mm to release the tool, it doesn't matter what taper you have it's the design of the pull stud gripper that does it......well mine does.

    I have the petal type gripper on my draw bar end pulling a pull stud in an ISO 20 taper tool shank.

    With a tool either in or out of the spindle the Bellville washers are expanded and are more relaxed than when pushed down to release the tool.

    That is all the pressure you have to hold the tool in the taper...…...you can't have it any other way with a draw bar pulled up with Bellville washers.

    The problem is that the Bellville washers are springy......pun intended.....they will compress down easily if they are at the end of their upward uncompressed travel with not much holding force, hence the ability of a tool to pull out of the pull stud gripper.

    Due to the fact that people like power draw bars that compress with air at the touch of a switch the problem will never go away.

    For arguments sake, if you manually pulled a drawbar up with a threaded nut like on a manual mill you cannot have the tool pulling down because it is a solid inflexible force holding it in......but who wants a manual solution.

    When my electric thruster (rated at 8,000 nm) type power drawbar motor failed I had to use a manual release mechanism ….this was a bar bolted across the top of the housing with a hex headed bolt in the middle to manually push the draw bar down...……..it takes 4 turns of the 16mm X 1.5 mm pitch screw with a 200mm long spanner to release the tool from clamped to unclamped...….. so that means I know the force holding the tool in is quite considerable.

    I think you could test the retention force of the washers by applying a measurable force to the end of the drawbar and see how much pressure it takes to start pushing it down.

    As the bar starts to move down the spring pressure will increase until it is at it's max when the pull stud gripper releases the tool.....that is a ludicrous solution for tool retention.

    As end mills, when cutting, exert a downward pull on the draw bar, the tendency will be to slacken the grip in the taper and make it rattle around.

    In my opinion, the only solution to the problem would be a hydraulic one to hold the draw bar up once secured as oil is incompressible, it doesn't take much pressure, just oil and a non return valve......but that needs designing.
    Ian.

    Last edited by handlewanker; 02-15-2020 at 11:20 PM.


  18. #38
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    Default Re: fretting on 30 taper tooling

    Actually, your description is interesting to me for a few reasons, not the least of which being that I think Dyna changed the pressing mechanism. My machine has some arrangement that doesn't seem to be anything like the original SKIP DM4400 machines. It has an oil reservoir as well as the two air lines for up and down. The thing was giving me grief because I was wondering how it was connected to the spindle, but it turned out to be easy. Four bolts and you wiggle it around a bit and the whole assembly comes off (after disconnecting the air lines and the Hall effect clamp sense board. After that, I suspect that my system on the DM4400M is very similar to what you have on the original SKIP machines.

    I've included a photo of what I see as I look down the hole in the top of the head cover. I can see a metric set screw in there but then it gets interesting. I put an allen wrench in there and I can turn it either clockwise or counter-clockwise but the screw never seems to loosen or tighten. I'm not sure what to make of that. I don't have a tool for the top end, so I'm a bit stuck right now. I was expecting that I'd need to remove that Allen screw in the middle, however, and then I could unscrew that bolt on the top. That part of the operation hasn't really been detailed in this thread, so if someone wants to chime in, that is fine by me.

    fretting on 30 taper tooling-img_2707-jpgfretting on 30 taper tooling-img_2710-jpg

    [added on edit]
    I have a bit more information on this. I looked at bolt/top as I turned the allen head. I was a little surprised to see that the *whole* assembly (meaning, the allen head, and the flat sided nut that is on top of the spindle, both turned. However, that turned out to make sense because I hadn't inserted the tool in into the spindle that captured the retention knob ball bearings. So, I went ahead and did that. I found that I could (fairly) easily remove an allen head bolt. Looking down into the area that the removed bolt's head vacated, I realized that there was a set screw that could then be unscrewed (the screw was bored out), as shown in the attached photo. Now I'm at a point where I need that special tool so that I can remove the top nut.

    What is still a mystery to me is another tool that was taped to the one for the retention knob (bottom end... I'm missing the tool for the top end). I've attached a photo of it. it clearly goes through the top nut now that the allen head and set screw have been removed. The thread on the end is the same as the allen head bolt. I am guessing that this is what the previous owner used to provide some downward force to preload the Belleville washers? It doesn't seem like the tool would work very well though. Anyhow, if you have thoughts, please let me know.
    fretting on 30 taper tooling-img_2713-2-jpg

    Last edited by MrMetric; 02-16-2020 at 10:20 AM.


  19. #39
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    Default Re: fretting on 30 taper tooling

    I made the tool for the top. I kept mine a little beefy so that I could make some alterations, if desired. The tool worked great BUT there are a few caveats....

    SOME IMPORTANT CONSIDERATIONS IF YOU ARE DISASSEMBLING THE DRAW ASSEMBLY!!!
    1. My top nut is a left hand thread. At least one other person had a right hand, so apparently there area few variations. My machine is a later one, however, so I'm guessing they switched to late (mine is a Mitsubishi Meldas M3 control)
    2. When you finally unthread the top nut, it *is* under pressure. Mine jumped about 2 inches and ejected some washers!
    3. When you unscrew the top nut, the drawbar will fall straight down. Keep a hold on the bottom tool so you don't eject it downwards!
    4. And... the ball bearings in the retention knob grabber at the bottom end can/will drop out if the drawbar has dropped anything more than an inch or so.
    5. Again, the ball bearings will drop out! Be prepared... I'm now looking for one that got away. [edit: yeah! Found it! It is my lucky day...]


    In the following photos you can see my drawbar. It was arranged with washers in the following fashion: ()()()()()()(), etc. Interestingly, I had 78 washers *not* 80. That might be why I only had 100PSI. Or, perhaps two got lost in the head. I'm going to go verify if that is the case.
    fretting on 30 taper tooling-img_2715-jpg

    Next up, you can see the thread on the top is left hand thread. Screwed into that is the set screw, which is hollowed out so that, finally, the Allen head bolt can lock the set screw down too.
    fretting on 30 taper tooling-img_2714-jpg


    Here you can see the tool I fabricated. It is pretty close to the one for which there is a drawing earlier in this thread. I put flats on the side for a wrench, which worked. However, you kind of need 3 hands this way. I think I'll probably but a bar in the side that is screwed in. I also bored a hole through the middle of the tool so that you can (un)tighten the set screw and allen head bolt. That hole has another purpose, though. I think it will be needed for the bar extension (shown below). During reassembly, that stub is screwed into the threads for the Allen Head bold and then goes through the tool (yeah, I will probably need to turn some of the tool down for room). Tightening down on the nuts there, will allow you to start the threads on the nuts. This will be a bit of a PITA, I suspect, but I can't see how else you can compress the Belleville washers enough so that you can get that nut on there. I'm a little worried about those tiny threads that are used to attach the stud to the drawbar.
    fretting on 30 taper tooling-img_2717-jpg
    fretting on 30 taper tooling-img_2716-jpg

    Last edited by MrMetric; 02-16-2020 at 07:29 PM.


  20. #40
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    Default Re: fretting on 30 taper tooling

    I decided that in the absence of comments regarding the need to "draw in" (aka 'compress') the top nut so that it could engage the threads, that the way my Belleville washers had been installed was incorrect. When removed, these had been in a ()()()()() configuration. There were 78 of them, but I did finally find four additional ones sitting on top of the spindle pulley. That would make 82, which is curious. I'm wondering if perhaps some were lost long ago when the previous own worked on the Belleville washers. Hmmm. And, on a side note, there was no O ring on the top when I took off the pressing piston.

    I rationalized that the bolt shown in my previous posting was probably not required if the Belleville washers were installed in a (())(())(()) type configuration because this would take less space than the other (either 78, 80 or 82... depending upon how many washers were really in there). So, armed with this, I decided to put everything together again because I was done making my top toll and McMaster Carr was incredibly fast, delivering my new washers today... The first thing I did was to arrange the washers. I've shown a series of photos. Because they didn't come out that well, let me cut to the chase. Measured from the top of the washer/collar on the bottom end, 80 washers stack up to a total dimension of 103.44mm or 4.073". This isn't really that accurate because there is slop in there, but that is about the distance you can expect.
    fretting on 30 taper tooling-img_2720-jpgfretting on 30 taper tooling-img_2721-jpg

    Next, I setup the drawbar, as shown below. Note the tray with the towel in it. This is *extremely* helpful in not losing the retention balls. In fact, I'd say it is mandatory for both assembly and disassembly. I inserted into the spindle until it was seated, and then put blocks under the lower tool to prevent it from dropping out.
    fretting on 30 taper tooling-img_2722-jpg

    I had transferred the Belleville washers onto a tee handle allen wrench and proceeded to drop them down into the hole on the top (remember the collar on the bottom. The serrations go DOWN. The following photo is what it looked like when I had all fo the washers in. about 1/4 to 3/8 of an inch (guesstimate) of the drawbar's thread was exposed, so no compression bolt was required.... I tightened the bolt, installed the set screw lock and then the secondary Allen bolt lock. And, finally I installed the pressing assembly (replacing the missing o-ring in the process.

    Great! Things went together incredibly easily and well. This really wasn't that hard a job... or was it... I powered the machine up so I could remove the lower tool and test the new clamping pressure. Guess what.... It isn't great. The photo below shows 400 PSI, which is nowhere close to the amount desired. Now, this is an eBay purchase and maybe it isn't working correctly. It is a pretty simple design though. The only things that can go wrong are air in the system, a bad gauge, or mechanical impingement someplace. The latter isn't likely, and frankly, the others aren't either. However, I will be sending the gauge back to the manufacturer for validation because I don't have any other way of determining if it is working correctly. Plus, Clamprite offers this as a free service if you don't request a NIST certificate. You just have to pay the shipping, which I'm happy to do.
    fretting on 30 taper tooling-img_2724-jpg

    I might be able to add a two more washers, but I will quickly get into problems if I add too many. Plus, I think this is jumping the guy. I should be able to get acceptable results from the stacking as originally installed. Maybe those McMaster Carr (PN 96445k247) washers listed earlier are not correct? Has anyone used these (and tested the holding PSI) with success? I don't know of anyplace else I can easily buy the washers, although I haven't really looked all that hard yet.



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fretting on 30 taper tooling

fretting on 30 taper tooling