[Oldmanandhistoy]

I am hoping to get about a 1.5:1 motor speed up with the new pulleys, which should give me close to 6,000 rpm, which should be far beter for aluminium than my X-1's 2000 rpm.

Hi again,

Don’t get paranoid I’m not following you lol

Just a quick couple of question; do you think you may have over heating issues running the spindle at 6000 rpm? The reason I ask is I have noticed in one or two threads (not sure if on the zone or else where) people have been concerned with very hot bearings and that would be at much lower rpm’s. Maybe they had too much preload?

Also what is the max rating on these bearings for rpm?

John

[digits]

Hi again,

Don’t get paranoid I’m not following you lol

Just a quick couple of question; do you think you may have over heating issues running the spindle at 6000 rpm? The reason I ask is I have noticed in one or two threads (not sure if on the zone or else where) people have been concerned with very hot bearings and that would be at much lower rpm’s. Maybe they had too much preload?

Also what is the max rating on these bearings for rpm?

John

I have to admit, I don't really know! I did see that RS sell all the bearing sizes that this head uses, but rated at 11,000 rpm, and I did buy a spare set from littlemachine shop just incase. I am also going to have 200kg of aluminium heatsink on my spindle, so it might not be too much of a problem

I was actually thinking of replacing the X2 head casting with a solid milled block of aluminium for increased stiffness, and I suppose I could actually flow all my flood coolant through that to cool the bearings if necessary.

Right now I just want to get the last few mechanical parts cut - I really want to see this thing assembled and moving in June!

[digits]

Well, it's been a very quiet week but I finally got a new X-1 motor on Friday and fitted it on Saturday. I then made the last 5 or so plates that I need to fit the X-axis on to the Z-axis and the head on to the X-saddle.

Now I need to make a couple of pulleys for my X-2 head/X-3 motor combination. First step is to bore it out to 30mm ID to fit the X-2's spindle. I started off by mounting my 3-jaw lathe chuck on the adaptor plate I made at the start of this thread and then indicating it central on my rotary table. I got bored at 0.01mm runout - but then again, I don't have any dials that can measure beyond that, so it will do!

First I used a 4mm slot mill to bore a large hole in my 50mm round stock, the rotary table spun and the mill stayed put.




My little 4mm end mill wasn't long enough to do the full depth, so I did half and flipped it:





Much to my surprise, the hole is too small! I wanted 29.5mm ID to allow for some finishing, so I figured 29.5mm/2 = 14.75mm, and my mill is 4mm in diameter, so I need to position it at 12.75mm off centre. When I measured the hole however, it's only 27.5mm across - what's wrong with my sums?

The surface finish isn't perfect either, so I thought I'd bring it up to 30mm with my boring head. I haven't even unwrapped this before - I've had it for atleast 8 months - oops! I'm not quite sure how to set it up - how do I meaure the diameter it will cut, and what angle should I set the cutter to? Anyway, here's a picture of the setup - it's too tall for me to be able to get the cutter out of the hole without removing it!



I'm going to do a search on how to use a boring head - I want this bore to be super-smooth as I hope this pulley will hit 6,000 rpm in use.

[skmetal7]

lol u are using your boring head backwards! i guess it doesnt matter, as long as your boring bar is in right. well we all learned at some point! u unscrew the screw not screw it in! u might want to use a shorter boring bar, it will defelct/chatter and leave a bad surface finish. turn the boring bar around, its in backwards. when u use it tighten the dovetail on the boring head as tight as u can and when u unscrew the dial screw to the size u want screw it back in a bit untill its tight, when its spinning the head will move out because of the backlash in the screw, throwing off the adjustment. just take several passes of about .010" or like a mm or two(never work in metric), and ull have a good finish.

and whats that long thing in your spindle holding your endmill? cant u just use a collet in the spindle? it would make it a lot stiffer and u would gain a lot of travel/clearence.

[Trapper14]

@skmetal I believe he is using a collet, just a weird long adapter kind of thing from the looks of it...
and about your diameter that you milled...well you notice its exactly half of the cutter, because you have to take into account the other side of the circle, so if you move it a quarter of the actual size, then when you think about it, that would be half the cutter! That probably doesn't make much sense, and its been a few months since I machined but I was confused by this same thing when I was CNC programming a circle by hand. Good luck, and keep up the good work!

edit: and one more thing, you really should move that cutter in more, so it isn't hanging out so far, chatter city!! rigidity is our friend

[acondit]

and whats that long thing in your spindle holding your endmill? cant u just use a collet in the spindle? it would make it a lot stiffer and u would gain a lot of travel/clearence.

That is a HighTechSystems quick change collet adapter. It uses ER16 collets. Except for the length it works real well. Some guys are using them to build ATCs for their routers.

Alan

[skmetal7]

im just worried about his endmill sticking out so far, i bet its deflecting and causing a lot of chatter, hence the bad surface finish

[Pres]

im just worried about his endmill sticking out so far, i bet its deflecting and causing a lot of chatter, hence the bad surface finish

What "endmill"?
The only thing I see "sticking out so far" is a boring bar mounted in a boring head.

Also, the length seems about right for him boring all the way thru it in one pass (which is best)

What am I missing that you see?

IMHO, with a good, sharp cutting edge and going slow it should work ok.
(sure, a lathe is a better tool for machining that part. but if you don't have one...)

Pres

[digits]

@skmetal I believe he is using a collet, just a weird long adapter kind of thing from the looks of it...
and about your diameter that you milled...well you notice its exactly half of the cutter, because you have to take into account the other side of the circle, so if you move it a quarter of the actual size, then when you think about it, that would be half the cutter! That probably doesn't make much sense, and its been a few months since I machined but I was confused by this same thing when I was CNC programming a circle by hand. Good luck, and keep up the good work!

edit: and one more thing, you really should move that cutter in more, so it isn't hanging out so far, chatter city!! rigidity is our friend

I was still scratching my head after reading this, but finally it clicked:

I wanted a 29.5mm diameter hole, so I should have taken half the diameter of the cutter off the diameter of the circle the cutter needed to travel, and hence the radius of the cut should have been 27.5mm/2 = 13.75mm not 12.75mm!

I had hoped to do a full depth cut with the endmill - but after working out it wouldn't reach, I really should have wound it back in so that only 25mm stuck out. My boring bar is fully in though.

[digits]

That is a HighTechSystems quick change collet adapter. It uses ER16 collets. Except for the length it works real well. Some guys are using them to build ATCs for their routers.

Alan

Yep - wouldn't be without it - I might even weld my drawbar in

Skmetal 7 - yes, I should have shortened my endmill once I figured it wouldn't go all the way through in one go! I think though that the finish is probably also hurt by the fact I had to go way beyond the depth of the flutes, even to get half way down - there's no TiN on the shaft of that endmill anymore!

[digits]

lol u are using your boring head backwards! i guess it doesnt matter, as long as your boring bar is in right. well we all learned at some point! u unscrew the screw not screw it in! u might want to use a shorter boring bar, it will defelct/chatter and leave a bad surface finish. turn the boring bar around, its in backwards. when u use it tighten the dovetail on the boring head as tight as u can and when u unscrew the dial screw to the size u want screw it back in a bit untill its tight, when its spinning the head will move out because of the backlash in the screw, throwing off the adjustment. just take several passes of about .010" or like a mm or two(never work in metric), and ull have a good finish.

and whats that long thing in your spindle holding your endmill? cant u just use a collet in the spindle? it would make it a lot stiffer and u would gain a lot of travel/clearence.

Thanks - I will redo my boring bar setup!

[skmetal7]

What "endmill"?
The only thing I see "sticking out so far" is a boring bar mounted in a boring head.

Also, the length seems about right for him boring all the way thru it in one pass (which is best)

What am I missing that you see?

IMHO, with a good, sharp cutting edge and going slow it should work ok.
(sure, a lathe is a better tool for machining that part. but if you don't have one...)

Pres

i was talking about the endmill in the first few pics, he has a lot of its sticking out and maybe thats why he has a bad surface finish.

[digits]

Well, I set my boring head up and had a go at boring out that pulley centre. Unfortunately I got a bit lost and took too much metal off



So I started again, this time remembering to drill a 5mm hole into the blank to form the key-way before I started cutting the centre out. I also wound my little 4mm end mill back into the holder to keep you guys happy and to try and improve the finish.


I have to say, it made a big difference to the finish - I will have to remember to keep all my mills as short as possible in future.


Here are my two attempts side by side - the correct one is on the right


It fits my X-2's spindle like a glove - next step is to set the rotary-table vertical, and carve some teeth into the outside of it. I'm not 100% sure of how I'm going to do that - I might have to write the G-code by hand, as I did for the bore.

[Trapper14]

Looks good!, I am glad you figured out the whole circle thing I couldn't quite figure out how to describe it, but at least you go the idea. Gear hobbing is fun, u will enjoy that

[digits]

Looks good!, I am glad you figured out the whole circle thing I couldn't quite figure out how to describe it, but at least you go the idea. Gear hobbing is fun, u will enjoy that

Thanks Trapper - I am not hobbing my gears - I'm trying to mill them:

I had a great deal of trouble mounting my rotary table vertically as it won't line up with two slots on the table of my X-1 and it is too deep to be placed in a single slot, pointing towards the column. Anyway, I did my best with clamps etc, and started out by milling a 1.2mm deep groove 10mm wide around the edge of the pulley, to give it some flanges:



This went pretty well, and then I sat down and tried to work out how I was going to cut the teeth. My plan was to cut slots with a 1.5mm slot-drill in the groove I'd already made, and rotate by 12 degrees between cut to give me 30 teeth. I was then going to run the program again, but with a 3mm ball-nose mill to give me a better tooth profile. Unfortunately I managed to hit my chuck jaws with the spindle, and I broke my gear-selector again - the 3rd time I've done it, so once again, my mill is out of action

I am going to order some more replacement parts for my X-1 - 2nd time in a week, and in the meantime, I've got 7 geckos and a Grex to wire up.

[FPV_GTp]

Hi

Very nice work digits

cheers

[digits]

Hi

Very nice work digits

cheers

Thanks - it's all trial and error really!

Hopefully the postman will have brought me some spare parts and some nice new carbide ball nosed mills today, so with a bit of luck I'll be able to restart work on my pulleys. The good news is that as I need to turn down one end by about 5mm anyway, I can afford to mill off those botched teeth and start again on the other end.

I have no idea how I'm going to do my 75mm pulley though - it is too big for one set of lathe-chuck jaws, and too short to be clamped in the other set without the jaws interfering with the cutter. Hmm, it might be another coaster!

[digits]

Well, I had another busy weekend of milling:

I started out by turning down my 50mm pulley's shaft:



Then I flipped it round and milled a groove to give the belt some flanges to keep in in place:



Then I switched to a 2mm solid carbide slot-mill and started cutting some slots for the pulley's teeth to engage in:



And when that was done, I opened up the slots with a 3-mm ball-nose mill:



My 75mm blank wouldn't fit in my 3-jaw 5" chuck at all - so I swapped to my 4-jaw 4" instead:



I turned down the shaft last this time:



And here are the finished pulleys:



Unfortunately, after all that hard work, they are useless! The rush-job counterweight I'd set up on my Z-axis was off centre, and tilted the spindle over to the left After all the effort I went to centre the 4-jaw on the rotary table, I forgot to check the spindle was trammed, and so these parts are lop-sided (chair)

I don't know if I'm going to try again, or just try and buy some appropriate pulleys and bore them out to the corect diameter, but right now I'm pretty fed up!

[S_J_H]

Well can't say I have never done things like that. I have made timing pulleys before. Nice job making them with the integral flanges though. I pressed mine on.
But they are cheap enough where unless it's some really crazy pulley size I need I'll just buy them now. It's just not worth the effort. Sometimes it is easier to just turn the shaft of whatever you need to mount the pulley on to match available bore sizes. I just built a new drive system for my lathe project I just started. I'll be using a DC mini mill motor. That darned motor has an oddball 9mm shaft and I can only find pulleys in 8mm and 10mm. So rather than fumble with inidicating in a timing pulley and boring it to fit, I took the motor apart and mounted the armature between centers and turned it down to 8mm. 15 mins work and now any available 8mm bore pulley will work.
Steve

[digits]

Hi Steve - during making these, I really did think, I really could do with a lathe right now! I have a head stock, tail stock and cross-slide, but to make it all work, I need, you've guessed it, a timing pulley for my motor!

I can buy a 44 tooth/75mm pulley with an 8mm bore hole for the motor, and then just drill it out to 1/2", but the 30 tooth/46mm pulley isn't available with a hub big enough to make a 30mm hole in to fit my mill-spindle. Fortunately, it's not as wonky as the big one, so I could just about get away with using it with a stock X-3 motor pulley, though that would give me a max speed of about 1500 rpm, rather than the 6,000 I want.