[Jdubya]

Ive decided to fill the void/hollow area in my gantry with epoxy granite. Then i will fill my Ibeam base voids.

That might dampen some of my harmonics.

Since none of it will be visible, should i just use sand since i dont care about the finish or looks? I am after rigidity.

[mactec54]

Ive decided to fill the void/hollow area in my gantry with epoxy granite. Then i will fill my Ibeam base voids.

That might dampen some of my harmonics.

Since none of it will be visible, should i just use sand since i dont care about the finish or looks? I am after rigidity.

You don't get rigidity by add sand it can dampen some of the harmonics but if you are cutting steel you will need a different spindle to do that successfully

[Jdubya]

You don't get rigidity by add sand it can dampen some of the harmonics but if you are cutting steel you will need a different spindle to do that successfully

When i said adding sand, i meant like an 80-90% sand and 20-10% epoxy mix. As in i am not trying to make it look like granite.

Any spindle recommendations?

[mactec54]

When i said adding sand, i meant like an 80-90% sand and 20-10% epoxy mix. As in i am not trying to make it look like granite.

Any spindle recommendations?

No spindles that are of the same type you are using are suitable for milling steel, the spindle bearing arrangement that is designed for these high speed spindle is where the problem is, apart from a cartridge type spindle and a independent drive motor I don't think there are any of this type of spindle that is made for low speed use just for steel or any type of metal cutting

If you take light cuts with what you have and have plenty of time for the job to be done you can use what you have, engraving should not be a problem, it's when using a Endmill it pulls down on the spindle releasing the preload on the bearings once this happens then you have a mess and it does not take much for this to happen

With the sand mixture unless it can bond to the steel or aluminum it is not going to make it anymore rigid, rigidity starts with the design of the machine adding pieces can help sometimes but it is always best designed for your needs at the start before you build your machine

[Jdubya]

No spindles that are of the same type you are using are suitable for milling steel, the spindle bearing arrangement that is designed for these high speed spindle is where the problem is, apart from a cartridge type spindle and a independent drive motor I don't think there are any of this type of spindle that is made for low speed use just for steel or any type of metal cutting

If you take light cuts with what you have and have plenty of time for the job to be done you can use what you have, engraving should not be a problem, it's when using a Endmill it pulls down on the spindle releasing the preload on the bearings once this happens then you have a mess and it does not take much for this to happen

With the sand mixture unless it can bond to the steel or aluminum it is not going to make it anymore rigid, rigidity starts with the design of the machine adding pieces can help sometimes but it is always best designed for your needs at the start before you build your machine

Thanks Sir! I have not seen much for low rpm spindles either. I see some interesting 5 bearing power heads with reduction gearing. ( might be interesting) would bumping up to 2.2kv+ 4 bearing with an ER20 collett help?

I never intended to be cutting steel with this machine but i do have the time and its seemed to work quite well with small bites. Thats really all i need for now as i am just milling holes and slots for now.

Now that this machine works. I can build the next machine differently.

[mactec54]

Thanks Sir! I have not seen much for low rpm spindles either. I see some interesting 5 bearing power heads with reduction gearing. ( might be interesting) would bumping up to 2.2kv+ 4 bearing with an ER20 collett help?

I never intended to be cutting steel with this machine but i do have the time and its seemed to work quite well with small bites. Thats really all i need for now as i am just milling holes and slots for now.

Now that this machine works. I can build the next machine differently.

I did find this Spindle which would be a 4 pole, don't know how they have the bearing configuration though and it is a high price

https://www.aliexpress.com/item/32996693858.html

[Jdubya]

I did find this Spindle which would be a 4 pole, don't know how they have the bearing configuration though and it is a high price

https://www.aliexpress.com/item/32996693858.html

Thats got a decent RPM range that i havent seen before, thanks. I will bookmark that for another day...

[Jdubya]

This spindle unit looks like it could work? . 8k rpms and mentions milling steel.

I would probably need to switch to the square linear rails instead of my round rails for my z to get any tight tolerances happening.

Im also thinking about embedding my vise into my frame/base when i do my epoxy fill. Its dovetailed on the bottom side so it would be permanently locked in. It would drop my vice jaws down 2 inches lower. Hmm

[mactec54]

This spindle unit looks like it could work? . 8k rpms and mentions milling steel.

I would probably need to switch to the square linear rails instead of my round rails for my z to get any tight tolerances happening.

Im also thinking about embedding my vise into my frame/base when i do my epoxy fill. Its dovetailed on the bottom side so it would be permanently locked in. It would drop my vice jaws down 2 inches lower. Hmm

Yes that is what I was saying when I said having a cartridge type spindle and independent motor, the weight can be a factor that you have to keep in mind with this type of spindle

[Jdubya]

I filled my gantry void with epoxy, sand and several sizes of gravel/pebbles. The gantry took less than a cubic foot. My base fame will need about 4 cubic feet.

I am also replacing my round bar linear rails on my Z axis with 20mm square linear rails. Ive got that about half done now

Still looking at different spindles for low rpm milling.

[mactec54]

I filled my gantry void with epoxy, sand and several sizes of gravel/pebbles. The gantry took less than a cubic foot. My base fame will need about 4 cubic feet.

I am also replacing my round bar linear rails on my Z axis with 20mm square linear rails. Ive got that about half done now

Still looking at different spindles for low rpm milling.

How did the Gantry work out after filling it

[Jdubya]

How did the Gantry work out after filling it

I am still rebuilding my Z axis rails so I have not cut anything yet, but it sure sounds different when hitting it with a rubber mallet.

[Jdubya]

I took a chance on that bt30 ebay spindle.

Looks like it should work fine..

[mjoconr]

I took a chance on that bt30 ebay spindle.

Looks like it should work fine..

I'd be interested in purchasing something like this. What do you search for ? who was the seller ?

Thanks
Mike

[Jdubya]

I'd be interested in purchasing something like this. What do you search for ? who was the seller ?

Thanks
Mike

Search bt30 8000rpm power head spindle and i went with a us seller in cali , yokimm

Very fast shipping.

[mactec54]

I took a chance on that bt30 ebay spindle.

Looks like it should work fine..

The only thing I see is the motor to spindle pulley ratio may be a problem having enough torque at lower RPM

[Jdubya]

The only thing I see is the motor to spindle pulley ratio may be a problem having enough torque at lower RPM

This motors rpm is fixed at 8000rpm, they offer the same one with different gears and belts that is 3000rpms

[Jdubya]

Closer.

[mactec54]

This motors rpm is fixed at 8000rpm, they offer the same one with different gears and belts that is 3000rpms

If the motor is 3Ph then you could use a VFD Drive and change the speeds if could run at

[Jdubya]

If the motor is 3Ph then you could use a VFD Drive and change the speeds if could run at

Yeah, Unfortunately, its only 110v, single phase with 2 amp draw.