PM727M Power Draw Bar Part 1

OK so with the belt drive in the testing phase and feeling good about it I'm moving on to the Power Draw Bar. In this video Part 1 I will work on the Draw Bar Sleeve.I have tried to be as detailed as possible to the point of being informative but not boring. I will try to keep the videos around the 15 minute mark. Please comment and let me know if the content is spot on or you would like more information and details. Thanks for watching , please subscribe, thumbs up if you like the video, and most importantly , Be Safe!
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[@ScotY808]

Looking forward to part 2! Nice job, Sam!

[@CNC4XR7]

coming soon Part 3 is the best part

[@JAMESHOPKINSIBXCNC]

Worked out pretty well there!! Great job Sam.

[@CNC4XR7]

yes sir it did. But I had help! :-)

[@russtuff]

Nice progress.

[@CNC4XR7]

russtuff thanks Rus

[@bobuk5722]

Hi. This looks really useful for me, looking forward to the rest of it. For the best accuracy - not really needed for this application as you will know, but maybe helpful for other folks tackling more demanding ones - turn a suitable thread onto a small arbor to take the top nut - that way no reliance is placed on the accuracy of the chuck, it's all down to the headstock bearings. Don't use a die on its own folks, they can wander, although they are useful for finalising the tread form after single point turning. Thread turning is an unecessary finesse for this job and it is sensible to omit it. What really attracts me is the thought that goes into your designs. I'm going to make use of it. Cheers. BobUK

[@CNC4XR7]

Thanks Robert, Happy to help! this was the simplest and most effective way, later on a permanent draw bar can be made.

[@bobuk5722]

Yes, me, again! What I'm hoping you will show is making the retention collet on the lower end of the drawbar. Those things are VERY expensive. BobUK.

[@SmallShopConcepts]

Robert in this instance these drawbars are for the TTS R8 type of quick change tooling. in this instance the collet is a simple 3/4" R8 collet with the face ground flat and can be had for about $15 from Tormach and works with the TTS type tool holders. you are probably looking for a more traditional type of retention pullstud gripper such as a claw or ball and socket type. but won't find that in this specific build. those type of retention methods require significantly more throw and a simple 3 stack of belvilles is not nearly enough to release that type of tool. those type of release mechanisms have stacks of belvilles in the 20's to accumulate the proper throw for tool release and also to not require the same amount of force to retain the tool as our methods do.

[@CNC4XR7]

I agree with Chris , The TTS system is a little more forgiving in terms of adaptability to manual mills with R8 spindles. The manual mill BT-30 spindles do not always have the space to accommodate a sufficient amount of Bellvilles to achieve the desired travel to release the pulls stud. This biggest concern with the TTS system is tool pullout there's only so much pressure you can get from the Bellvilles. A TTS collet cost about $30 US stay away from cheaper imports as they do not have the Flat bottom. www.tormach.com/store/index.php?app=ecom&ns=prodshow&ref=35356

[@buildmotion1426]

Very nicely done. Have you looked into a hydraulic intensifier? I saw one many years ago with a manually operated lever. But small pneumatic cylinder would probably operate it fine.

[@CNC4XR7]

yeah I have seen those however the cost is to great.

[@centurialinc]

Very cool! I am having the same dilemma with the air cylinder, I only have 100psi. The belvil washers are not very strong because the air cylinder has to be small and thus also not very strong. So I am getting some tool pull out if I run it harder. I'm going to try and squeeze on a 4 inch air cylinder from amazon to see if that will get me some more power. Best Matt

[@CNC4XR7]

i suggest you go the same route I did by using a 80mm bore vs the 100mm bore. space is tight up top. the same force can be had by applying more PSI to the air cylinder 150 - 170psi gives me 3500 lbs of force. Home depot has a great little compressor that puts out 175psi for around $230 20 gal. but if your dead set on 100mm let me know I have a brand new one same one Tormach uses on the 1100.

[@gunracksonline]

I used the 30gal 175 psi husky air compressor from home depot. Within a year it blew the head off. I used it to operate a air cylinder on my small mill at a little over 150 psi and it eventually blew the head off. Luckily it had a 2 year warranty and was fixed under the warranty.It took almost a month to get it back from repair. I ended up getting a air cylinder that had more Lbs of force at a lower pressure. I can operate it off a ridgid twin tank think its 4.5 gal. at 100psi. So with the pmv mill i will probably do the same thing.

[@CNC4XR7]

Good Info thanks, I have a 100mm bore 3 stage air cylinder as well , however the geometry on the PM727m makes it really tight to go with the 100mm bore. The 80mm fits really nice. The Husky compressor may have been just a lemon ? the working cutoff is @175 psi so it's not like were asking it to do anything it was not designed to do. At least I hope that is the case :-) The air cylinder is rated for 150 psi i'm running it right around there so I suspect early O-ring replacement is possible. i will keep a eye on it. Thanks for the heads up.

[@centurialinc]

CNC4XR7 Well in any case, I'm going to attempt the 4inch air cylinder. It is the lesser expensive route. Also it's for my fully custom gantry mill so i have more freedom in the design. I'll let you know when I get to that point what I end up doing. And i have the auto tool changer working for five tools! I love it! I'll have a video on that for you soon. Best matt

[@Marvin.Runyon]

When Belleville washers are under compression, does the ID change? Wondering how snug a fit the sleeve can be, to keep them from becoming unbalanced.

[@CNC4XR7]

Balance is not really a Issue. I would say the ID does change slightly

[@juanmanuelgarciaortega2591]

hola donde compraste ese piston?? gracias

[@CNC4XR7]

El china

[@williamhardin5254]

That looks nice. How much weight do you think you are adding with this set up?

[@CNC4XR7]

well its about 120lbs total so not that much really the weight I removed from the gears were replaced by the air cylinder. so its a wash really

[@SmallShopConcepts]

if you are referring t just the drawbar alone it is much less than 120lbs, probably closer to around 15lbs, i think Sam was referring to the motor upgrade, bletdrive and associated other parts included.

[@williamhardin5254]

That's what I figured he meant by the comment he left. I knew the drawbar addition would not add that much weight. Thanks for the reply.

[@rc-cnc3431]

Nice job. What model of pancake cylinders are those? Where did you get them?

[@CNC4XR7]

I ordered them from China MOQ was 10 these are 80mm 3 stage.

[@rc-cnc3431]

@@CNC4XR7 I looked all over last night no luck lol

[@CNC4XR7]

@@rc-cnc3431 SDA80 is the model # try ali express

[@skirkdouglas]

Sam, having trouble finding the air cylinder. There are different strokes and what I have found don’t have all the air hook ups like yours. Would you mind putting a link to the 80mm and 100mm? Thanks

[@CNC4XR7]

Kirk Douglas There hard to find try searching SDA 80-15 80mm bore 15mm stroke 3 stage. Look to pay $130 - 160 and about $80 shipping if you buy from china.

[@skirkdouglas]

CNC4XR7 no luck. Can’t find anything for 3 stage cylinders

[@CNC4XR7]

Shoot me a Email

[@skirkdouglas]

CNC4XR7 email sent

[@CNC4XR7]

Double Action or Single action Spring return may be used . Definitely use a 3 stage to have any chance of using the bigger Bellvilles.

[@Marvin.Runyon]

So your belleville stack is setup for about 1200lbs? (100mm diameter x 100psi)

[@CNC4XR7]

MarvinRunyon No I have about 3500lbs on my Belleville springs 150psi on a 3 stage 80mm bore

[@tomhutchins1046]

That 150 psi may be a mistake high pressure compressors are not real reliable unless its a true commercial unit then they use lots of power and of coarse if you pop a hose or fitting at that pressure DUCK!!! I have owned a machine shop for over 30 years

[@tomhutchins1046]

kzbin.info/www/bejne/hn-ZZYebqL-ebJI This and one of his early videos had some interesting info

[@CNC4XR7]

Thanks Tom I'm aware of the risk using 150psi the working pressure of the bellvilles are 2750lbs but that's to get them working the flat load is a little over 4000 lbs @150 psi i'm at 3500lbs . I will run the mill and see if my machining habits cause any tool pullout and I can reduce the air pressure if warranted. The Air cylinder i'm using is a 80mm bore a 100mm bore is ideal but the extra size makes it a little more difficult to fit.