[Azalin]

I used 1.1mm Belleville washers in )))((()))((( configuration. If I remember correctly it was 400-450 kg force. The cylinder should have plenty force for it.

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[RCaffin]

Hi Azalin

Did you put hardened steel washers at the ends of the Belleville springs? Without those in place the Bellevilles will chew up the aluminium surfaces.

Cheers
Roger

[mactec54]

Hi Azalin

Did you put hardened steel washers at the ends of the Belleville springs? Without those in place the Bellevilles will chew up the aluminium surfaces.

Cheers
Roger

What aluminum surface, the spindle is steel

[RCaffin]

Yes, the spindle is steel, but what about the two surfaces the Belleville washers are bearing against - the end cap and the piston? They are aluminium I think?

Cheers
Roger

[ianagos]

What aluminum surface, the spindle is steel

True but putting in hardened steel washers can’t hurt. Can it?

[Azalin]

Roger,

There are no belleville washers used in the cylinder.

Yes, the spindle is steel, but what about the two surfaces the Belleville washers are bearing against - the end cap and the piston? They are aluminium I think?

Cheers
Roger

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[handlewanker]

Hi, I wouldn't think Bellvilles could be used to retract the spindle away from the draw bar end (even if they could be fitted), just not enough travel .......and I can't see how a spring is going to be fitted to the cylinder spindle end...... the inside of the cylinder would not have enough clearance to fit one there unless it was designed to be in there in the first place..

Simply, if a collar was attached around the spindle end then a coil spring could act against it and the face of the BT30 housing to push the piston(s) back......that would mean you only need a single acting solenoid to push the pistons out with the spring retracting it......auto return.
Ian.

[RCaffin]

Hi Azalin

My mistake. The Belleville washers are on the BT30 pull-rod - yes?
Actually, now I think about it, I can't really see the need for a double acting cylinder. Surely the strength of the Belleville washers would be enough to push the piston back?

Or have I misunderstood again? Quite possible - I have had the flu badly and am still recovering.

Cheers
Roger

[handlewanker]

Hi Rog, yes the Bellvilles in the BT30 spindle will push the draw bar and the piston(s) back but that means the air cylinder spindle will always be resting on the draw bar end when it's running......friction will mean a worn end.......the purpose of a spring is to keep it slightly clear when retracted.

Bad luck with the Flu....get well soon sport......did you have the Flu jab ?
Ian.

[RCaffin]

A worn end - I guess so. Unless an 8 mm hardened steel (or carbide) ball and a good blob of grease could serve? In a cup?

Flu - no jabs. We (wife & I) never bother, any year. I only got sick this year because of some other injuries, which did nobble me a bit. Normally we just get a sniffle for 1 or 2 days.

Cheers
Roger

[Azalin]

Hi again,

I bought an Optimum BF20L Vario benchtop mill some time ago, just to put this spindle on however the head must be replaced because stock head is too small to fit my spindle in. So I designed a head and intended to use full 7075 aluminum. The required aluminum chunks weigh about 25kgs and its too expensive. So I need to think about other options, which are:

1- Iron casting. Making the mold is the easiest part. Casting and stress relieving can be done in any casting place and stress relieving will cost some. The hardest part is to find a big mill to surface the faces. I haven't done any casting before. I don't know what else I will face.

2- Epoxy Granite head. This is probably the cheapest option but again, a big mill is required for the faces.

3- Similar option to EG is concrete casting.

What do you think?

Thanks again,
Suat

[ianagos]

One you forgot about is weldament. That still involves machining large surfaces though. You may be able to surface the important parts with the mill in its stock configuration as well.

I’d say either do it of 6061 or weldaments.
Casting would be optimum but probably expensive.

[ebrewste]

I’d say either do it of 6061

Agree. If you need 7075 over 6061, you are doing it wrong - just leave more material for strength. Most of the time in machining, if it is rigid enough, it is strong enough.

[handlewanker]

Hi again,

I bought an Optimum BF20L Vario benchtop mill some time ago, just to put this spindle on however the head must be replaced because stock head is too small to fit my spindle in. So I designed a head and intended to use full 7075 aluminum. The required aluminum chunks weigh about 25kgs and its too expensive. So I need to think about other options, which are:

1- Iron casting. Making the mold is the easiest part. Casting and stress relieving can be done in any casting place and stress relieving will cost some. The hardest part is to find a big mill to surface the faces. I haven't done any casting before. I don't know what else I will face.

2- Epoxy Granite head. This is probably the cheapest option but again, a big mill is required for the faces.

3- Similar option to EG is concrete casting.

What do you think?

Thanks again,
Suat

Hi, do you actually have enough material to bore the existing head casting out to the diam of the new spindle body?

Whichever way you go the existing head casting with the quill spindle will not be wanted again in that mode.

Whichever way you go anyway you will need to do machining of sorts...…..just boring the existing casting out to a bigger diam is less work as the dovetails are already on it...…..unless you also are considering adding linear rails to the column.


BTW....an aluminium casting...per se..... would not weigh as much as a solid chunk of ally as it would be hollow inside.


An ally head casting would mean less weight to heave up and down.
Ian

[RCaffin]

You certainly don't need 7075 for that. 6060 or 6061 would be fine, and a lot cheaper. A couple of bits 25 mm thick would probably do it.

Note that cast iron would weigh 3 times s much: not a good idea to add that much weight. EG would not be a good choice anyhow as parts of it would be under tension, and could/would fail.

Cheers
Roger

[handlewanker]

Hi, there is another way but it's extreme surgery …….first you cut off the complete existing quill housing from the head casting to leave you with half the casting depth.

This will probably leave you with a hollow cavity behind where the quill housing was after it's cut off......that is, no flat face to bolt a new spindle body to.


Then you bore two holes 30 mm diam top and bottom through both sides of the head casting behind where the quill bore was to take two steel bars..


Then you make an ally housing from a solid billet bored out for the new spindle body to fit against the casting and bolt it to the two steel bars that the 30 mm holes were bored for.


Yes, it is major surgery but it would give you a head with a BT30 spindle and using the existing motor and belt drive.
Ian..

[Azalin]

Ian,
It is really impossible to use the stock head. But the good thing is the head and the part that has the dovetail is separate. I bought the aluminiums.

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[TOTALLYRC]

Looks like blank sheet of paper to mount your spindle ideas to.


Mike

[handlewanker]

Hi, of course, I forgot the head is bolted to the back and has a sideways tilt design to it......you are indeed a happy chappie…...no need to cut the head casting at all

This means it would be the same for many other manual mills too like the SX3 etc...….removing all that superfluous iron at the front part would make the head so much lighter......there must be at least a couple of hundred kilos of metal you won't have to push up and down now.

Now all you have to do is design for the motor and drive mechanism...….also a power drawbar...………...at the same time you could consider linear rails for the column, that is one area where it would pay dividends even if you stayed with dovetails for the X and y axes...…..balls crews are going to be a must have no matter what...…...you is gonna be a busy bee ...LOL.
Ian..

[Azalin]

Ian,

I've been thinking of using a counter weight to the head. But the weight will be on the bench and not on the column. So all the load including the head will be removed from the column.

Second thought, the counterweight can be a little lighter than the head. What do you think?