I have only found some surprisingly expensive sources for these and wonder if anyone knows of a cheaper source.
HEGONG SPRING supply professional and honest service.
The size I am after is the same as the ones used in a Unimat 3. Touch under 35 o/d and a touch over 17mm bore. I have found a source for the smaller ones used in the earlier unimat in the UK and a bearing kit plus the disk springs from the USA but I really need to buy locally and it doesn't make any sense to pay shipping costs on the bearings.
Just like the unimat 8 light ones would be ideal. I believe they are about 1mm thick or a touch less.
John
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If they were the correct unimat ones I would need 8. Assoc Spring does have the correct size in belleville at around £3 each, bit more if I buy 4 a bit less if I buy 8. Don't know why but I hate paying that sort of amount for something that probably cost pence to make. This sort of thing really annoys me, probably because I have bought for industry via an account. The discounts on some items are fantastically high especially in the bearing area.
However if I look at disc springs there is a part 36mm dia with an 18mm bore to din that works out at £0.45 + vat each for 8. I feel a file with them all mounted on a mandrel will sort the diameter out. The main difference with the parts is that the belleville comes correctly sized for a bearing.
I suspect the unimat ones are significantly thinner than either of these which are around 1.2mm but that shouldn't matter really.
Thanks for the offer Clive. The springs are stationary so have to fit the bearing o/d bore fairly well and always leave clearance on the spindle. There is a problem with Assoc Spring – I have to buy 32 of them. They are 32p each then but if all else fails.
John
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Posted by KWIL on 26/07/ 10:22:57:
That will be 1 3/8" x 5/8" then in real measurements
I agree but the bearings in a unimat 3 are a metric type – so have to work in sensible sizes to 1." for the bore they fit in. Could be that 1 3/8 is too big as I guess they expand when compressed. The "correct" belleville is 34.93 diameter which is 1 3/8. As the dearer ones appear to be imperial spec'd in mm that might explain the price. Working out the conversion must cost a lot of money.
Me thinks filed to size is the best option now. I don't seem to be able to find any stated as being bearing preload types of the right size.
The older unimat ones are on ebay uk. Those could be used against the outer end of the bearing against the inner race and preloaded with a nut. The unimat 3 uses them internally pressing against a circlip and the outer race of the bearing so it's all neatly enclosed in the housing. Lots of springs can be used easily that way. Not sure about 32 though but more is better.
John
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Posted by Jesse Hancock 1 on 26/07/ 12:23:06:
John W1, possibly because you know they are made by the million and probably cost a fraction of a penny each.
Time was when a trip to the works stores or work shop would secure such things in sweepings off the floor.
However these days the punter has little choice but to pay up.
I'm close to Redditch – still much the UK home for making springs. One company does them in bags of a hundred. I did think about hanging around there one lunchtime ……………….. It might turn out that it's now more of a warehouse than a factory though.
Around £20 for 32 including postage and vat isn't too bad. I looked at adding a couple of circlips to the order and it came up POA. !!!!! Simply bearings should have those anyway.
I did think about making them. I do have a heavy lump hammer but no steel of a size suitable for the formers and I would have to buy some silver steel in black bar as it's cheaper. No idea what the reference to it is – I just tell the supplier what I want. Maybe they could be spun but looks to me like costs would be a significant proportion of what they cost to buy.
Time now to look at what I can make the body out of. Bar would involve a lot of swarf.
John
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Searching for DIN with UK in front of it was worthwhile – a supplier charging 50p each so just ordered 10. A saving over having to buy 32 but not all that much. These are 0.9mm thick, just hope that proves enough.
**LINK**
It's odd that DIN doesn't cover actual bearing sizes but maybe there is another standard.
Leesprings ?????? No way. £6 each. I had looked there earlier. I'll bet they just love small orders.
Edit – Dam – silly me just realised I can only use 8 if they are doubled as per a unimat.
John
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Edited By John W1 on 27/07/ 00:08:56
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Running a new production job on a Mori Seiki Duravertical cutting low carbon steel plate with a 1/2in 5 flute end mill.
I'm taking a modest cut ( rpm .002ipt .05 WOC) and noticed after a dozen parts or so that the end mill was making a lot of low end vibration and noise. I inspected the tool but it still looked brand new. After pulling the holder out, I was shocked to see what looks like fretting to me on the taper.
The spindle is not even at 30% load so I'm surprised to see it but after thinking about it, I'm starting to suspect the drawbar force is low and the washers need to be replaced which brought up a couple questions.
1) What are the odds do you think my issue is caused by low drawbar force? (everything else is solid, work holding, program, etc)
2)The machine is nearly 15 years old but the drawbar force has never been checked to my knowledge. The machine has really low hours for its age but what is the expected replacement interval for the washers?
3) Anyone have experience replacing the washers in a Mori? How difficult/long of a process is it? Can it be done without having to realign the ATC arm?
A drawbar force gage is $700 which is the most logical thing to buy to verify but if replacing the washers is simple enough then I'd rather save the money and just replace the old washer to see if that fixes my problem.
You will want the force gage even if you change the washers.
That is how you know how tight you need to tighten the washers up.
Another place to look is the collet inside the drawbar, assuming mori seiki used that type of tool retention. Some designs have a thread-in collet that is on the end of the bar. Those replaceable collets can wear and cause low clamping pressure. The collet can usually be removed from the taper side of the spindle.
Other drawbar designs can utilize balls in a taper. That type requires you to remove the whole drawbar from the spindle.
No matter what, though, get the gage.
Go to Haas Tooling. They have the ISO40 drawbar force gauge for $346. It's backordered right now.
I don't have theirs but, I do have one. I checked my own Haas and found it dead in the center of the range specified in their documentation. I also checked a friend's VF-5. It also was dead in the middle of the specified range. The point being that having the tool means you can check that box and move to the next problem.
Next culprit: are you torquing the pull studs? After buying a pull-stud socket, I discovered I had been over-torquing studs. Excessive torque causes the top of the taper to swell slightly. That can cause the holder to mate tight up at the top and leave the bottom in looser contact. That's obviously the opposite of what we want. I'd buy a socket, check the manufacturer-recommended torque values of your holders and stick to that.
Last time I tried to buy them, Mori was no longer selling the collets or washers separately. You now have to buy the entire drawbar assembly.
Also, if I may offer a piece of advice that you didn't ask for. Get rid of those US Shop Tools pull studs. In the picture on the left, that line that you see right at the 'T' of USST is the mismatch from the radius side near the holder to the 90° shoulder. That stress riser is exactly where they break. Cost us $30k to replace a spindle on a 5-axis Mori because of one of those failing (cracked right through the taper). On the flip side, we had saved $10 on the stud.
Last time I tried to buy them, Mori was no longer selling the collets or washers separately. You now have to buy the entire drawbar assembly.
Also, if I may offer a piece of advice that you didn't ask for. Get rid of those US Shop Tools pull studs. In the picture on the left, that line that you see right at the 'T' of USST is the mismatch from the radius side near the holder to the 90° shoulder. That stress riser is exactly where they break. Cost us $30k to replace a spindle on a 5-axis Mori because of one of those failing (cracked right through the taper). On the flip side, we had saved $10 on the stud.
I appreciate the heads up. The pulls studs are quite old as well and deserve to be replaced. Thoughts of destroying the spindle is just the motivation I need to get off my butt and finally do it!
How much did the drawbar assembly cost you? I'd imagine the washers must be a common item if I could match them.
Thanks for all the feedback. I looked into the pull stud bulging the taper as I've never heard about that before and sure enough, our CMM could pickup the form difference between a really tight stud and no stud. Form difference was about ." and the taper angle shifted .04 degrees near the pull stud.
I bought a brand new holder to replace the fretted one and blue'd up a couple to check the spindle taper fit. @DavidScott was exactly right, there's no contact near the stud. Also I'm no blue wizard but it looks acceptable to me. What do you all think?
Went through a similar issue on our HURCO VM10i recently. It's only a few years old so was surprised the drawbar force was on the low side although still in spec. I decided to change them anyway. It was easy enough and while your machine is different I would imagine the process would be fairly similar. I've linked to the thread below.
It didn't really help much (slight improvement but still does it with larger tools) so I've decided that the machine is probably just not up to the job of using large tools that stick out of the spindle significantly.
I'm currently going through a Bellview washer replacement after having issues with cutters breaking prematurely and some spindle fretting. The drawbar force is below spec so I've decided to replace the Bellville washers. I've spoken to HURCO and they don't have a procedure for this and I'm...
Wanted to circle back on this as we finally got our Haas drawbar gauge in from back order.
Funny enough it has an M16 pull stud thread so we had to go out and buy a BT40 stud to be able to use it. I did notice BT40 studs have a longer neck length which I am not sure if that would affect the measurement. It looks like the stud provided by Haas also is longer than their CAT40 stud.
Any-who the measurement on both our mills came out the exact same to ~lbs. The sheet with the gauge only lists BT tapers and says BT40 is 500-. However Haas's website says 942-. Talk about conflicting info.. so I called Mori and the guy said it should be -lbs.
Do any of these numbers sound correct to y'all? I searched some forum posts and one guy claimed lbs what should be used.
Interesting enough the Mori tech said he more often sees the drawbar fingers wearing out than the washers which can cause low retention force. The downside is a drawbar assembly from Mori is $.
Running a new production job on a Mori Seiki Duravertical cutting low carbon steel plate with a 1/2in 5 flute end mill.
I'm taking a modest cut ( rpm .002ipt .05 WOC) and noticed after a dozen parts or so that the end mill was making a lot of low end vibration and noise. I inspected the tool but it still looked brand new. After pulling the holder out, I was shocked to see what looks like fretting to me on the taper.
The spindle is not even at 30% load so I'm surprised to see it but after thinking about it, I'm starting to suspect the drawbar force is low and the washers need to be replaced which brought up a couple questions.
1) What are the odds do you think my issue is caused by low drawbar force? (everything else is solid, work holding, program, etc)
2)The machine is nearly 15 years old but the drawbar force has never been checked to my knowledge. The machine has really low hours for its age but what is the expected replacement interval for the washers?
3) Anyone have experience replacing the washers in a Mori? How difficult/long of a process is it? Can it be done without having to realign the ATC arm?
A drawbar force gage is $700 which is the most logical thing to buy to verify but if replacing the washers is simple enough then I'd rather save the money and just replace the old washer to see if that fixes my problem.
View attachment
Put a prybar between holder and spindle and give it a little pry action it should be hard to budge if you can move it your definitely weak on the springs. I think you might be able to rent a tester and check all your machines and document all the readings
Don
I don't know if I have official numbers from Leadwell, but our mid 90's leadwells with bt40 and cat40 spindles are about lbs.
Also don't know about official numbers, but our Kitamura cat40s runs about lbs
Length of pull stud will make a huge difference in force.
I recently replaced the drawbar collet on a kitamura hx400. The "collet" screws into the drawbar from the taper side. Force on that machine was like lbs and it was causing issues.
The kitamura tech support on the told me to look at the collet first before bothering with the springs. I pulled it out and noticed a noticeable worn step in them. Replaced it with a new collet and force was back up to lbs.
FWIW we use a clamprite force gage.
I would be making 100% sure that the studs that you have been using are the correct ones, as well as the ones for the gage.
The stud you need to use is the correct stud from your machine. Do not use any other stud as length, diameter, and angle all make a huge difference. There are hundreds of different pull studs, and bt ct use different adapters to the force gauge. If your stud doesnt thread to the gauge, you have the wrong adapter. Whether Haas allows for the other adapters I do not know, the other guys (command-ott, etc) allow the gauge to be adapted to virtually all different styles of knobs.
I just looked over all my prints for that spindle and none of them call force out specifically. So I looked at the last 3 of these that we have rebuilt, all of them landed between -lbs.
Trust the numbers from Mori. Every make and model is setup different so you cant just say a 40t from Haas should pull the same force as a Mori. Even if you just look at Haas they have at least 5 different specs for 40t drawbars retention force.
Its very likely that you are getting a low reading due to the wrong pull stud. The stud you are testing with is longer, allowing the drawbar to relax further lowering force. The data is useless.
The stud you need to use is the correct stud from your machine. Do not use any other stud as length, diameter, and angle all make a huge difference. There are hundreds of different pull studs, and bt ct use different adapters to the force gauge. If your stud doesnt thread to the gauge, you have the wrong adapter. Whether Haas allows for the other adapters I do not know, the other guys (command-ott, etc) allow the gauge to be adapted to virtually all different styles of knobs.
Its very likely that you are getting a low reading due to the wrong pull stud. The stud you are testing with is longer, allowing the drawbar to relax further lowering force. The data is useless.
While I agree, the stud supplied directly by Haas with the gauge is longer than their standard CAT40 and as far as I know, Haas doesn't have a BT40 machine.
I couldn't find anywhere that sells a CAT40 stud with an M16 thread to exactly match our Mori stud but the extra length is the same amount between the two Haas studs. After doing a little more digging it looks like Haas applies a correction factor from the gauge to drawbar force rather that reading it directly like all other drawbar gauges I've seen.
Seems you need to multiply the pressure reading by 1.55 to get the correct force. If I do that to my measurement I get lbs which is just below the range stated by Mori.
I wouldn't think 200lbs would be the difference between fretting and not fretting but I'll see if I can get the collet out of the spindle for to look for wear.