Prazi BFE65-Littlemachineshop Big Mill table Frankenbuild, spin off thread.

[RaisedByWolves]

All righty then, Now all I have left to do is everything.

Now that the scales and the light are finalized Ill be turning my attention to the power feed.

I have an idea of what I want, but I'm not sure how far I can take it with the items at hand. I know I want it to be Bridgeport like in layout and function, I'm just not sure until I really get into it how close I can get.

I started out by making the right hand side of the mill table in accordance with my plan. I started out with a hunk of steel 4.75x4x2". I know what I want is inside it, I just need to remove everything that is not the finished product and what's left will be the finished part. I'm purposely making it bigger than it will probably wind up in its finished state, just so I have enough material to make my idea work, and because I may also come up with a few more ideas along the way.

First off I located and drilled 3 holes copied from the original part on the mill table. I thought I had pics of this, but you'll have to use your imagination. Once I had the holes drilled (After squaring and bringing the block to size.) I began hogging out the unnecessary bits with a 1.5"carbide shell mill.

Somewhere along the line I also set up the rotary table and bored out the bearing pockets similar to what is in the factory end plate, but I apparently didn't take pictures of that either. I know I had done this previously because you can see it in these pics. It was a good amount of work with one side being 1"x.480 and the other being 1"x1.300 deep. Just pretend I showed you as there was not much to see as the action was deep in a pocket.

I started milling the wider parts that needed to be removed as to save time and reduce having to go over the different cuts more than once, or biggest to smallest if you will.







Then I went at the smaller section with a 3/4" endmill.






Then once I had my "Island" roughed out, I went back to the rotary table and began milling the island to size.

First with a standard endmill,








Then with a 3/32? radiused end mill for the final shape and size. You can see the bluing showing where Im just about .010 away from the final finish diameter here.






Once that was all done I realized I had a problem, none of the four roughing cuts from earlier wound up at the same height? Depth? Whatever, so I decided to keep it in the rotary table and take a .010 cleanup cut making a circular pattern across the whole part.








This was kinds time consuming/difficult/annoying as I had to stop every quarter turn to move a clamp. Speaking of turns, did I mention how many damn times I had to turn the handwheel on the rotary table up to this point? I'm thinking somewhere in the neighborhood of 500 revs to finish it. I would have done the math but I was too tired once I thought about this.

But the end result turned out nice.






Hey lookit! My one hold down clamp is all catawampus.

I hate that.

 

[RaisedByWolves]

Got to actually use the mill today for a project vs just working on it and it worked great, even if the learning curve was a bit steep.

I needed to make a pocket in a motor mounting plate for the Prazi lathe to install the Custom Crafter motor and control kit I got for it. I had the plate fabbed up previously but I needed to make a pocket to set the motor depth to get the motor pully to align with the lathe pully.


I started out gentile taking about a .050 DOC and outlined the pocket.





Next cut was .100 and I felt I was pushing it a little hard with the poor surface finish bearing this out, but I was hogging and the machine seemed OK with this so I kept on.








On my 3rd pass I noticed things were feeling a little weird and when I came back to where I began I realized why. The endmill slipped down in the collet. You can see the pronounced step in what should be a parallel surface right in front of the hole in the side wall of the pocket. This added about .060 to the original .100 cut and came close to ruining the job.





I never really cared for ER collets when milling due to this possibility, but again, I'm still learning this machine and the tooling and I was cutting quite aggressively. I choked the endmill up in the collet about .400 and tightened it up a bit more than before and all was good.


This is .100 DOC and 100% of a 5/16" endmill @380rpm. You can hear a slight hum as cutting a slot like this was taxing the machine as far as rigidity goes and you can judge the rate of feed with the DRO shot.

And this is about 80% of a 5/16" endmill at .250 DOC. like I said, I was hogging.

Now you might be wondering why I was pushing the machine so hard to make this pocket. It was because milling a .250 deep pocket 3.200x3.200 with a 5/16" endmill is a hell of a lot of handle turning. On a Bridgeport I could have had this finished in 1/2hr using larger endmills to clear out the majority of the material and smaller ones for the details. But here Im limited in the size of the tooling I can use and given that this took the better part of two hours. Granted, there was time taken up in the "Learning Curve", but given that a larger machine will always be faster at removing material.


I finished the pocket with .020 depth of cut and the same for the sidewall of the pocket climb milling and it seemed to do very well.

Finished piece was quite nice if I do say so myself.

 

[WobblyHand]

Not saying this was the problem, but I did discover a while back that ER collet nuts take a lot of torque. An ER-32 nut requires 105 Nm or 77 ft lbs. The dinky wrenches you get are way too short to apply enough torque without cheaters. When I was looking for ER-40 wrenches it was a struggle to find ones long enough. Longest I could find was about 10". The ER-32 wrenches are much much shorter, like barely 6" long. That means you need over 150 lbs of force to generate the correct torque for an ER-32 nut. Apologies if you know all this. Anyways, I sure was surprised at the ER collet nuts torque specs.

 

[RaisedByWolves]

Not saying this was the problem, but I did discover a while back that ER collet nuts take a lot of torque. An ER-32 nut requires 105 Nm or 77 ft lbs. The dinky wrenches you get are way too short to apply enough torque without cheaters. When I was looking for ER-40 wrenches it was a struggle to find ones long enough. Longest I could find was about 10". The ER-32 wrenches are much much shorter, like barely 6" long. That means you need over 150 lbs of force to generate the correct torque for an ER-32 nut. Apologies if you know all this. Anyways, I sure was surprised at the ER collet nuts torque specs.

No I did not know this.

Here I was being gentle with them as I ponied up for the ball bearing nut.

The nit was actually somewhat loose when I rechucked the cutter.

Got lucky really as the extra pocket depth to clean that up didn’t hurt anything save for my pride.

 

[RaisedByWolves]

Man its been 3 months since I did any work on the mill, been pimpin out the SD300, and this build was sidetracked as I didn't want both machines down at the same time. Things going like they do sometimes I was forced back at this one as I sold my lathe and mill motor to a fellow board member and I'm now forced to fit the Custom crafter motor and drive to the mill. No big deal really, Ive been enjoying the Custom Crafter drive on the lathe so much I've been looking forward to this.

I took the old motor off and removed the side cover to find out how the old motor was coupled to the input shaft of the gear train.

Found a coupler and when I tried to remove it it wouldn't budge.

That's it with the hole in it.




I was really hoping this was just a slip coupling and not joined to the shaft with a press fit or other method that would require me to remove the input shaft. I needed to remove it in order to modify it to fit the larger 15mm CC servo motor shaft.

Used a bit of technology (Iphone) to look and found a little screw holding it down.








Once that was out I bored it out 1mm to fit the new shaft. I then put the two motors side by side to check shaft length, and found the threaded portion of the new motor shaft was going to have to be removed.










Before.






After.







With that done I replaced the coupler and its hold down disk and screw. You can see the clearance around the disk where I had to bore it out.






Then I got it all mounted back up and tested it out. In testing I heard an odd noise and running it with the mounting screws loose there was a slight wobble to the motor and mounting plate. So I tore it all down and took some measurements. I found the .025 (a little more than 1/2 of 1mm) I took off of the key to allow for the coupler having been bored was just shy of enough, Ill need to take .010 more and it should be good.

Oh, yeah, I had to make a new mounting plate too.







The key is only half engaging the key slot in the coupler, but there's a gouge in the new plate that I dont like and this mounting plate is 1/8" thicker, so Im either going to flycut this plate thinner or I may just make mounting holes for this motor in the old thinner plate.

You can see the grease mark on the key showing how much engagement there is. Its probably plenty but more wouldn't hurt. I say plenty as this is a 750W motor whereas the original was only 290W or so, and with this head having plastic gears it will never shear the key.

 

[RaisedByWolves]

Been a while since I made any headway on the mill, too many other projects but I’m back at it now.


Just to finish up where I left off, I decided to fly cut the motor plate and got that all finished and have been enjoying using the mill with the variable speed drive. So much more user friendly and also quieter as now I can select the quietest gear out of the four and run it there for the most part.






What I've been working on lately is the X power feed. This is the Micro Mark unit which I chose over the Little machine shop unit as it was something like $50 less and basically the same thing. Didn't come as a bolt on item due to it having a different mounting plate, but I knew this when I ordered it and didn't care as Ill be making a new clutch housing that will bolt on directly.

I decided to make an entire new clutch housing and clutch mechanism as I: #1 want to make this lever operated from the right hand side like a Bridgeport as mentioned above, and: #2 I also want to make a better clutch mechanism. Essentially I plan on taking the entire drive unit apart and incorporating most of the controls into the right side end plate I made for the mill the table.

The factory clutch for this unit has a very nice simple on off function and as is its quite nice in feel and function, but it wont work with my lever idea.

Basically this is just a disconnect for the drive so you're not trying to back-drive the motor when using the handwheels.

Just turn the nob on the front to engage:







Or disengage:









And this lil spade end inside the brass collar:









Slides over the end of the cutout in the leadscrew shaft.










Simple, effective...........Boring.



So I came up with a better mousetrap.



Tried to come up with some off the shelf ideas and thought about a love-joy coupling or milling something similar to the toothed knee handle on a Bridgeport, but these Either were too big, or too time consuming to make, then I hit on the idea of making a pin clutch.


Basically this is a series of disks with engagement pins and drive pins and some springs. When the mechanism is moved to the right it engages, and it disengages when moved to the left. The drive disk will have three pins pressed into it that the clutch will slide on, and springs to facilitate engagement. The clutch will also have three holes to mate with those pins and three pins pressed into it to engage the clutch dog.

The springs are necessary to allow me to throw the handle for moving the table, and conversely letting the handle move the switch in the proper direction whether the clutch pins and clutch dog holes are lined up or not.

Clear as mud?


MS paint for clarity. The springs are omitted in the drawling, but they will go between the drive and the clutch.

Nothing is to scale.....Nothing!




This will all work off of a new clutch housing drive shaft labled "Drive" above.



Having the idea roughed out and having needed the rotary table to be setup for another project (<<<What got me off my ass to start working on this again) I of course started at the end and began working my way forward. This was out of necessity as I had to turn down a larger piece of tool steel than necessary, so while it was being turned down and to keep concentricity I turned the clutch dog, bored it and parted it off, then did the same with the clutch.

This gave me all three pieces necessary without making multiple unnecessary setups.


So then it was off to the rotary table.

Once I setup my chuck to hold the parts, I used an 1/8" endmill to bore out the holes instead of drilling as I knew they were going to break out of the wall of the back of the clutch dog and didn't want to risk either the drill or the reamer walking off.


Poking the holes. Yes I have an endmill in a drill chuck, don't care. I'm basically using it as a peck drilling operation so no big deal in my opinion.







Then the holes were reamed with a #29 reamer to give a .136 hole.








And then chamfered with a Center drill. I chose the center drill as it had the most forgiving taper out of the tools I had at my disposal. I really just wanted some lead for the pins to ride on going into the holes. This will give plenty of clearance for the .125 drive pins and also allow easy disengagement under power.


Finished product.








The holes breaking out of the back side of the clutch dog is an unintended bonus as it will let any debris that might get in there to have a way to either fall out or be flushed out without having to disable the entire works.


Still needs a couple of 1/4-28 setscrews to drive the shaft, but the hard part is done.

 

[RaisedByWolves]

Got into a quandary over the last couple days as I missed an important detail in my design and the drawing above.

I have pins to engage the clutch to the clutch dog, pins from the drive to drive the clutch, springs to make engagement automatic (bear with me)when I throw the lever…..

But no way to force the clutch to retract the pins from the clutch dog!

The hell was I thinking?


I’ve kinda been in a hurry as I have one of our mills tied up with the rotary table, so there’s that….

Anyway, I scrambled around this morning looking for some pre made item to help cut some time out of this operation and hit on something simple that should be durable enough and easily replaceable if they fail.

Pics of f where I’m at so far.


Clutch and clutch dog mating parts.







Fits nicely.







The solution to extracting the clutch….6-32 cap screws and springs that are waaaay too long at the moment.







These three cap screws will go through three holes in the drive disk and in conjunction with the springs, either drive the clutch allowing it to float if need be before engagement snd also extract the clutch pins from the clutch dog when needed.








Next I’ll need to disassemble the factory clutch to get an idea what the drive shaft/driven disk and engagenment mechanism needs to look like then I can move forward with that.

We’re rolling now!


.

 

[RaisedByWolves]

Last week I got around to disassembling the Micro-Mark clutch engagement mechanism and found it to be fairly simple.

It’s basically a shaft with two machined in washer with a second shaft coming in at 90* with an offset pin on the end that when rotated moves the feed engagement in and out.

The shafts bare nekkid.





And in the clutch housing showing how the two shafts interact. You can just make out the cam pin in the pic






Looking this over gave me enough information to go ahead and make the last clutch part, the drive shaft. Nothing remarkable here so no pics, just more lathe and rotary table work and Viola, I had another piece of the puzzle made.

That is it on the right. It has through holes for the 10-32 cap screws that drive the clutch mechanism and spring pockets for the springs to ride in. Having pockets for the springs is crucial as it retains the end of the spring to keep it from squirming around and causing the spring to either break or pop out of alignment and get bent.






Still need to put a chamfer on the pockets, but I need to make a special tool as a standard counter sink is too pointy to work in the shallow pocket.

Here's how the whole thing looks and will work when finished.

The whole shebang with the drive pins engaged.





Clutch with drive pins disengaged. I'm simulating the parts in position as they will be assembled by holding them by hand.







Clutch engaged with springs compressed, but not yet driving clutch dog needing rotary motion to line pins up with pin pockets. Things are a little off kilter in the pic and I had to use the table to force the springs down.











Closeup of clutch with pins engaged and driving feed.