Thread: Keeping up with the Jones

Originally Posted by Michael G

The inserts are all CCMT - in this case a Sandvik CCMT 09 T3 08-PM.
However, the thing doing the cutting in photo 5 is actually HSS. I've found when cutting Al that you get a better finish if you rub the surface with a candle (even better if the part is warm as the wax is then half melted and flows a bit more). The finished parts have been cut with a mixture of HSS and insert. No special Al inserts. I do occasionally think about it but don't do enough Al regularly to warrant them.
The live centre is indeed a Piper although I could not tell you what the preload is as I've never taken it apart.

Michael

Very nice work there Michael, is the candle wax better than Kerro or metho for surface finish on aluminium do you think?

Originally Posted by Michael G

The inserts are all CCMT - in this case a Sandvik CCMT 09 T3 08-PM.
However, the thing doing the cutting in photo 5 is actually HSS. I've found when cutting Al that you get a better finish if you rub the surface with a candle (even better if the part is warm as the wax is then half melted and flows a bit more). The finished parts have been cut with a mixture of HSS and insert. No special Al inserts. I do occasionally think about it but don't do enough Al regularly to warrant them.
The live centre is indeed a Piper although I could not tell you what the preload is as I've never taken it apart.

Michael

Like you I don't turn a lot of aluminium but the high positive Kennametal 5010 CCGT inserts I use on steel cut 6061 like butter and leave a nice surface finish, well at least to me.

I have a Piper, it sits in its wooden box because of the preload. It's good for supporting work up to 200 kg hence its lack of use.

Originally Posted by Ropetangler

Is the candle wax better than Kero or metho for surface finish on aluminium do you think?

I've always been told that kero is the go for Al. I tried candles because they are (supposedly) made from paraffin wax and they do seem to work. I haven't used kero as such but do use CRC, WD40 etc as (again) I've been told that kero is a major constituent. I find the wax a little more user friendly as it does not spray everywhere. The liquid stuff is useful on the other hand for directing down holes or slots where the wax can not go. The wax is probably the first thing I reach for but more for convenience as both seem to do the job. All I can suggest is try it and see how you go (the candles are the 6 in a box supermarket ones so not expensive. If you don't think it works as well, at least you are set for the next earth day).

Michael

Originally Posted by Anorak Bob

I have a Piper, it sits in its wooden box because of the preload. It's good for supporting work up to 200 kg hence its lack of use.

I use mine for everything - no issues with doing small parts or large parts. I'm getting confused though - the 200kg bit is the amount of weight that can bear on the centre (that is, a vertical load that it is supporting), not a force that has to be applied when using the centre?

Michael

I wasn't suggesting the 200 kilos was the force required for the thing to function. My understanding was that the preload was required due to the centre's high load carrying capacity. I could be miles off the mark !

I have turned a stack of ally of late, both 6061 and 601(? castings). I've used CCGT's and the equivalent high positive polished round inserts. FWIW Michael i have about 6 of those buckets plus i have already cast about 4kg worth!

Since i was doing so much i thought i would try a few different lubes, wax, straight kero and WD. In both types of ally the finish when using WD was better than the other products hands down Rather than spraying it everywhere i found just filling the insert worked a treat.

Attached pic is a bit of 6061 parted off, outer cut with kero, the rest with WD40. Pretty easy to see which gives a better finish!

Those pulleys do look good, nice to see the project coming along, more than can be said about any of mine!

Originally Posted by Ueee

...a bit of 6061 parted off, outer cut with kero, the rest with WD40. Pretty easy to see which gives a better finish

Agreed. I have a hand spray bottle of the stuff and find it is great for popping a few drops where needed.

For those who haven't turned much Al before it is worth pointing out that the best reason for using a lubricant on Al is because when it cuts it can sometimes form a thing called a "built up edge", where a lump of Al attaches to the tool tip. Murphy's law says it typically happens on finishing cuts in critical bores for example. This can wreck your surface finish as well as alter sizes (the edge effectively makes the tool longer). A good lubricant will stop this happening, so while I cut dry for most things, Al is one where I do tend to use lubricant, especially for finishing operations.

Michael

Hi Michael,

Those pulleys look good. That figure of 1/8" per foot of belt for cresting is a nice figure to remember. I always wondered how that was determined. Using WD40 etc to reduce the chances of chip buildup is also another tip I will steal.

Simon

It's strange but one of the best parts of a project like this is putting the parts together. Although looking at shiny new parts gives you a sense of having done something, having them fitted adds to the sense of achievement.
Today I took one of the pulleys and mounted it on a shaft.

P1030059 (Medium).JPG
At least I can now get a measurement for a flat belt and once the VFD is installed (one of those still to be answered "where" questions), see how well it turns over.
The frame is unpainted because with a job like this you can bet that there will need to be bits added, cut away, welded on etc etc. Once I have all the 'stuff' mounted I'll strip it down and paint.
One thing that may be of interest to others is the isolation method I've used. Flat belts are good at taking out vibration but that is not very effective if the motor is rigidly mounted to the frame that the grinder sits on. In the original the wooden base unit is relatively large and houses the motor and the top shaft is driven by a flat belt that is probably 7 or 8ft centre to centre - plenty of (physical) isolation.
What I've done here I hope will help though. The photo shows the base of the top frame where it bolts onto the table the grinder is on. The flange (40x40 angle) is sandwiched between a strip of 6mm thick insertion rubber and some rubber washers of the same material. Rubber is really good at damping down high frequency vibrations, so I'm hoping to have very few problems. On the other side of the plywood is another piece of angle (welded to the 50mm tube frame and nyloc nuts, to prevent loosening off.
P1030058 (Medium).JPG
I had hoped to get the wheel head shaft in place as well but that's a job for next weekend I think. One of the problems with that is going to be the belt tensioning device. The original design had several shafts going between the two sides of the overhead structure, some of which were there as pivots for swinging arms. I haven't got the space for all that so I'm going to have to improvise again.

Michael

This weekend was a bit slow, mainly due to not being here but I did get some shed time today and managed two milestones.
Firstly, I made up a housing for the VFD, fitted and wired up the motor. In I think what must be a first, the wiring did not have to be changed to get the motor running in the right direction (The plan is to lock out reverse as nothing will work in that direction - hence forward has to be forward). I still need to fit the remote start and stop buttons but it works. Hoots along at 1497rpm, which was a little surprising as even in the unloaded condition I was not expecting to be that close to synchronous speed.
P1030060 (Medium).JPG
As it seems to have worked for the SG, I've put the VFD in a chimney again with a hinged flap on top. This and the other VFD were second hand and came with fans fitted to them so for light use throw enough air around that the flap being open becomes optional.
The second thing worth noting is that the second shaft is now on. The third is the nasty one as I have to devise a clutch arrangement to drive the workhead, but the second drives the wheel head and now with these two in position I have been able to measure for belts and so should be able to order them.

P1030062 (Medium).JPG
Fitting the belt to the wheel head is awkward as it requires dis-assembly to get it on the pulley. However, I did not want to disturb the bearings multiple times, so when I attempt to fit the belts I'll also be checking the bearings and fitting the oil lubricators.

Michael

Hi Michael

Nice to see the little beast coming together - great credit to you as usual.

With regard your overhead drive and the issue of isolation, a couple of thoughts come to mind as possible means to further improve the isolation issues:

1. Firstly, as a means of helping to absorb vibration within the overhead frame with all the various rotating masses, consider filling your fabricated frame with concrete to increase its mass. This will lower its natural harmonic frequency range of the frame as well as making the ratio between the rotating masses and the static mass of the frame larger thus reducing the impact of any vibration generated. This is a simple thing to do - but only after getting everything on the overhead finished.

2. Secondly, depending upon where the grinder is to be located, is the idea of mounting the overhead frame on the wall behind or from the ceiling above, thus isolating it completely from the grinder - except through the flat belts. Of course this makes it harder to move to another operating location should the need arise.

No criticism of your overhead is implied with these thoughts, just the usual "How can it be done better?" question that arises in my mind when in the midst of the creative process of problem solving.

Look forward to your progress as you have the time.

Regards

Quentin

Thanks Quentin
I had not considered filling the frame (although it is possible). One thing I was going to do was perhaps add some sheet steel fill in pieces (say 3mm thick) to the front and sides of the frame to stiffen them up. I'm in two minds there as I think I'm reasonably well isolated so not sure how much stiffening things up will change the chatter seen on the work surface. I'm hoping to get things running and see and then if necessary take extra steps when stripping down to paint. Provided I can get a smooth round surface I may not chase improvement too much as my main use will be exciting things like ground pins and tapers.

Attaching to a wall or ceiling would do it of course but then I lose the portability.

Belts are on order so who knows what I may be able to get done this weekend.

Michael

Originally Posted by Michael G

Attaching to a wall or ceiling would do it of course but then I lose the portability.
Michael

You want portability? Have I got a deal for you!

When you have it finished, I swap you for a TP grinder!!!

Simon

Originally Posted by simonl

YHave I got a deal for you! When you have it finished, I'll swap you for a TP grinder!!!

Sorry - got one of those. I have a plan for it one day to grind the ways of my lathe. Hasn't happened yet. More courage needed I think.

Michael