what belt?

[Omnimill]

The last belt I bought for my milling machine was not in stock at Halfords at the time so I went to a local Motor factors and got one there. Most towns seem to have a Motor factors if you do a search.

Vee belts hold up well to speed change abuse - belt slipping between pulleys, not sure how well it would work with other types. If you're not belt slipping then just get the easiest available.

 

[blighty]

now that i have paid Mr Customs the 46% "because we can tax" tax,i now have my bearings.

should of put something next to them for a bit of scale:wall:

 

[Niels Abildgaard]

Why three belt disc sets?
My Lathe VFD is used from 8 to 80 Hz regularly and I have cut thread in direct drive at 4 Hz.

 

[blighty]

Why three belt disc sets?
My Lathe VFD is used from 8 to 80 Hz regularly and I have cut thread in direct drive at 4 Hz.

i was recommended by the guys i got the motor from not to run the motor any lower then 35Hz. lower than that i would need forced cooling. any more than 80Hz the bearings wouldn't last to long. as to how long and compered to what i don't know..... so thats why i went with 3 sets.

but in the end, i had some problems turning up the last 152mm pully, so i just went with the 2 in the end.

 

[blighty]

right the.....

done a bit of machining over the weekend and noticed a few things.

the lower end of the spindle gets a bit hot. it has been doing this for a bout a year, even before the belt change. when running at about 2000 rpm it gets really hot. and this is only after 5 min of running. i put this down the the bearings. so i thought i would change them out for the nice new ones. also when the spindle gets above 1600rpm there is a loud knocking noise. i thought this would be fixed with the new bearings.

done the change today. ran the spindle up to 2000rpm. it seems the temp problems have gone but the noise is still there. i think it may be coming from the top set of bearings. im also thinking it could be the way have mounted the pulleys. the pulleys on the spindle side are mounted to the spindle directly. as there is a bit of play between the spindle and the drive it may be slapping around in there. think i might have to redo the pulleys.

 

[blighty]

doesn't time fly........

just a recap...... when i first did the mod i mounted the pulley's strait to the spindle. this i think was making the banging noise. a few months back i took out the spindle drive thing and machined off the gear. then turned it upside down and put it back in. (bit hard to explain with no pics, but im at work at the mo and really board) then mounted the pulley on to this. so now the motor is turning the drive that turns the spindle (like before i did the belt mod) and not the spindle it's self.

much better, but there is still a slight banging noise. next thing was to put a thread and a nut for the top end of the drive/pulley bit, that when done up will pull all the slop together. did this at the weekend..............banging noise still there.:wall:

i took the spindle out and ran the motor. dead silent. all your could hear was the motor and a slight hum from the bearings holding the drive. put the spindle back in and the noise is back. (should of said....... the noise is coming from the top end i.e the drive/pulley) thinking it might be a lining up problem, i took the head apart and hammered out the dowels that line the top of the head up with the bottom. put it all back together, nipped up the screws and turned the motor on......... noise almost gone. i think with a bit of persistence i should get it lined up.

from seeing other belt mods on the net, i don't recall ever seeing this sort of problem. they all seem to be real quite from the word go.

i will stick some pics up. the above might make more sense.

 

[DJP]

Have you checked run out of the pulleys? They can stretch and release a belt on each revolution and that causes noise.

My cut off band saw has this problem but I ignore the banging as it's a crude machine doing a crude job. Adding a few more set screws to the bad pulley might help but it's a low priority repair.

For a milling machine I have to agree that quiet is good.

 

[blighty]

Have you checked run out of the pulleys? They can stretch and release a belt on each revolution and that causes noise.

My cut off band saw has this problem but I ignore the banging as it's a crude machine doing a crude job. Adding a few more set screws to the bad pulley might help but it's a low priority repair.

For a milling machine I have to agree that quiet is good.

dont think the pulleys are out, the id and od was machined at the same time with out removing the pulley from the chuck. the od is a sliding/push fit, but there is no reason why i shouldn't check them.


pic time......... first i would like to apologize for the crap job i made of the Paint.jpg's

the pic below are how the set up was.
when you do a belt mod, you take the drive out and turn it upside down. you then put the pulley on and lock it all up with a nut.

 

[blighty]

to the real thing.....

i know its all a bit heath at the mo, but once iv'e sorted it all out i'll make good and proper.

as you can see the spindle is stuck out the top of the drive. when you remove this and start the motor all is quiet. this is why i dont think the is any thing wrong with the set up in the pic. you get the noise only when the spindle is put back.

the spacer in the second pic is where the other pulley will go.

as i said, it does seem to of made a difference after i took out the dowels. it may just be a case of things being slightly out of alignment.

 

[blighty]

well........ shes all up and running.

i think the noise coming from the top pulleys was a lining up issue. for those that don't have an RF45 there are two dowels the line up the top cover with the body of the head. seems they where a bit out. so i took them out, put the cover back on and with the use of an alignment tool (big hammer) got it all lined up. no more noise

findings........

with the other pulley fitted top end speed is just shy of 5000rpm @1.3gg's
works out that the ratio ended up 2.18 and not 2.2 like intended.

cutting.....

got some numbers (speeds and feeds etc) and gave it a go.
with the stated power numbers came back with....
6082 T6
12mm end mill (1/2"ish)
3640rpm
22mm doc
1840mm'min (72in/min)
1.7mm step over (0.066")

cutter hit the T6, a stream of ali shot out from the cutter, just like the big boy cnc's like you see on YouTube then the cutter slowed down and stopped! mill then turned into a shaper for a bit

if you turn the rpm up it just get louder cutter still stops.
if you turn the feed down cutter dont stop, but your now going backwards, so whats the point of speeding it up in the first place.
ended up with 1mm step over works a treat.

to cut at them speed, looks like i need to do two things.
1. get some more gg's.
2. less of a steep over.

again, going over some numbers it seems i wont need any more than 4000rpm and that would be for the smaller cutters 6mm and below. but saying that it will still be cutting 4 times faster than it used to.

if i remake some pulleys around the 1.78 mark that should give me the 4000rpm. that would also mean i can run the motor at 80hz should also get me up the 2gg's mark. then it might be able to cut at the 1.7mm step over.

or i could try slot cutter (2 flutes)

other problem is the amount a swarf it makes and trying to clear it. my flood coolant wasn't up to the job. i had to get in there with the air line and blow it out the way. i can either find a coolant pump that spits out a million gallons a minute or go the way of the mist coolant.

think i will go with the mist as don't want the man cave flooded.

 

[blighty]

just had a thought. it might be a VFD setting that's at fault as to why the spindle stopped.

thinking about the old set up...... 1hp motor, turning the spindle at 1700. that works out to be .8hp ish. in that set up the cutter would explode, snap or throw the work out the vice, but never once has the cutter/motor ever stopped.

maybe there is a setting in VFD that sets the amps.

 

[blighty]

just found something out about the vfd i have..... there is a button on it that once pushed will show the amps the motor is pulling.

3hp motor running at 80hz @2240rpm =1.4amps.

1.4 amps that cant be right, ill run a tool path tomorrow (under load) and see what it says.

 

[blighty]

done some more playing with speed and feeds........

12mm cutter
22mm doc
3mm step over
3800rpm
900mm/min

amp read out on the vfd goes up to 6.7 amps when cutting at that speed.
seems to like 2mm step over better @1100mm/min

this is all grate and all, but now i have another problem..... HOW MANY CHIPS DOES THIS THING MAKE

when its not throwing them all over the work shop, there jamming up the cutter. at the mo i have have been flooding it with coolant and also giving it a blast with air.

so i'm now looking into the pro's and cons of mist coolant or "very" flood cooling.

flood cooling seems to be the easiest, but saying that, it seems you need around the 8000lt/min to blast the chips out. i have seen a few people on the old intermerwebnet using fish pond pumps (i have been using one for years, but its only 500lt/min) i have found a pump that comes in at 10'000lt'min and around the £100 mark. thats the easy bit. the hard bit is getting said 10'000lt/min back in the coolant tank.

mist... is all down to the compressor. i have found a few that are up the job. most misters need 10 to 20 psi @200lt/min or over 5cfm. but so far i haven't found a definite answer to how much you need. plus the quietest compressor i have found is 74db.

thought this hobby machining was meant to be fun:wall:

and the compressor i have now just took a nose dive:wall::wall:

 

[mcostello]

Your purchases are just starting-- making chips like that You will have to get a chip baler, forklift to move all, big truck to take chips to the scrapper,etc. Rof}