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Tool holder cuteness


compared to what I normally deal with at my job these things are adorable ๐Ÿ™‚ I strated thinking about spindle needs on my build and know what direction I'm headed so I'm starting to think BT30 spindle build. started gathering some parts and will be working on designs for the parts I plan on making myself. the plan is to make most of the spindle cartridge myself to try and save some money on this build. obviously this is just in the very early stages.

I just can't get over these little BT30 holders. normally I work with CAT50 tapers and CAT40 tapers and always thought the CAT40 tapers were small since I work with 50's most of the time.

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been messing around with this spindle design for over a week now. I think I have most of it sorted out. lots of stuff on it's way but the cost is more than I would have liked but it is what it is. but here is a screen grab of the basic concept of this thing. main body is 4.750 in diameter and the end flanges are 6 inches in diameter. should be a pretty solid spindle. the housing is split just so you can see inside on some of the stuff going on internally.

forgive my modeling I don't waste to much time getting into details other than the important stuff.

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seems like I've been at this spindle forever now. But I'm getting pretty close to being finished with this thing. I was curious as to how much this monster was going to weigh and as of now withย  no bearings and a bear shaft it's well over 40Lbs I'm going to guess somewhere around 50lbs once I get everything installed inside with the drive pully attached. hopefully this week end I can get it together to see what kind of run out I end up with? I had the shaft in the lathe and had a 70mm holder stuffed in the end and got about .0001 with no retention force and just friction holding the tool holder in place. that was a good sign but hard to tell until everything is together honestly.

I chose to make the entire spindle from 4140 HT pretty hard material but not as hard as a hardened spindle shaft on a commercial machining center. But this is a hobby machine build and only having a 1HP servo driving the spindle I think it will hold up just fine and still be well made.

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Wow!! Thats impressive. Huge but impressive! Good job.

@ecs I have a 100mm air cylinder that will mount on the head unit once I start that part of the project. when I get to that part I can start setting the stroke length for the spring loaded retention for the pull studs on the tool holders. I ended up buying the 4 pedal type for the 45 degree pull studs I'm using. most builds use disc spring stacks for the drawbar retention but I found a die spring that had the specifications on force needed that fit into my spindle shaft. since this is a smaller taper a die spring was an option. the larger tapers would require the usual disc spring stack since the force on a 50 taper gets around 5000 lbs of retention force. the 30 tapers range from 900 to 1200 lbs of force. the die spring i'm using maxes out at around 1800 lbs.

the plan is to have an ATC on this milling machine scratch build so building my own spindle saves me the trouble of figuring out how to mount everything to someone's designs. plus I got to pick bearings that handle heavier loads. I looked around and seen some spindles of this type but the bodies were only 80 to 100mm in diameter and the materials used were lacking on the housings on most. when you start thinking about spindles the bearings are the focal point along with the spindle taper. so it's important to use some high quality alloy in these particular parts of the design.

@machinedude Looks like a crazy build dude and totally agree with not having to modify someone else design to make it fit! And over engineering things is totally something i'd do.

I dont fully understand the stroke nor the different retention loads but it sounds like you have it all worked out haha. I'll be watching this post to see the progress and to learn!

Keep up the good work!


I got a good bit done over the weekend but it appears the run out monster is not going down without a fight. having never built a spindle beforeย  I can say it is a good leaning experience for me. so it looks like the best solution is to put the thing together and true the shaft taper up with a tool post grinder. it's amazing how so little runout in the taper can magnify so much out at the end of the tool. Plus I think the tool holder was not setting well I noticed some excessive deflection in the taper. not something noticeable until it was together and you start to push and pull on things with a indicator on it.

regardless I have come up with a solution and will keep moving forward with this thing. I made a cheap tool post grinder that should actually work pretty well out of a die grinder with a 1/4 collet. I probably won't get back to working on it until the weekend but at least it's a long weekend ๐Ÿ™‚ if it don't work i'm only out less than $30 and need a plan B I guess ๐Ÿ™‚

had a little time to mess around with things and think the cheap set of ER20 collets that I picked up on amazon might be a big part of my problems. I need to try a different size and see if I end up with the same results? the tool post grinder work pretty good I was able to touch up the taper and it seems to have fixed the seating issue that caused the deflection. the tool holders seem to run pretty true but as soon as the collet is put in and the tool things get weird? I have no doubts the cheap holders and collets factor into things I just have to find out which ones I can live with and what can be made better. as of now the collets seem to be the trouble maker or at least the 1/2 one in the set I bought.

lesson to be learned is cheap is not always the best path to take I guess ๐Ÿ™‚

@machinedude machine will only as good as the weakest part. Pointless spending extra on the good bearings ect... if you run the Chinese collets!

Quote from ECS on April 18, 2019, 3:31 am

@machinedude machine will only as good as the weakest part. Pointless spending extra on the good bearings ect... if you run the Chinese collets!

this would be the exact reason I did not want to take a chance on a spindle from china. I've seen similar spindles for a little more than what I have invested in the one I'm building but seen some things people posted on other forums that turned me off on the idea. I did buy the pull stud gripper from china. that ended up ok but took 2 months to get it here. I'm not good at waiting that long for something ๐Ÿ™‚

as for the cheap collets they are not ground on the I.D or deburred and you can clean them up and get better results than out of the package but they still suck on run out. seems like the china products are ok if you have a quality control driven company behind them. I have bought stuff from SHARS and had no problems but you are paying more for a babysitter to police quality as a result. SHARS has a ER20 set for around $90 I would take a guess and say the accusize brand on amazon is made buy the same company just under a different brand.

the cheap ones I got were as bad as .015 of run out? that's just not right to even be selling to people since they will never work and were marked as .ooo5 run out . I could probably fix most of them up to a point to being used on garbage work but would never think about any kind of precision work being done with them.