Gantry advice please

[Crunch]

Thank you for all your information.

I think I will go with
1610 x 900mm x 2 for y axis
1610 x 1200 for x axis ( gantry )
1605 for z axis ( still sorting out the lenght )
Going to get ends machined to suit pulleys.

20mm square linear rails all round.

Does this sound ok ??

Thank you

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[Clive S]

Going to get ends machined to suit pulleys.

The bit where the pulley is fitted is called the f length 25-30mm is usually fine BUT remember that the f length is included in the total length of the screw.

Standard machining for the f length is about 15-20mm.

Make sure you get the better bearings AC type for the screw as some suppliers will just put in simple bearings in the blocks.

[AndyUK]

Thank you for all your information.

I think I will go with
1610 x 900mm x 2 for y axis
1610 x 1200 for x axis ( gantry )
1605 for z axis ( still sorting out the lenght )
Going to get ends machined to suit pulleys.

20mm square linear rails all round.

Does this sound ok ??

Thank you

Sent from my SM-G900F using Tapatalk

Your X axis is quite long for 16mm - You'll get a 12mm root diameter on these, which means assuming you use a BK and a BF, you'll have a max speed of 1000rpm before whipping. With the 10mm pitch you're okay because it sets your max rapids of 10m/min - definitely wouldn't want to go 1605 though! A 20mm screw instead will give you a max rpm of 1260 which bumps your possible rapids up to 12.6m/min, but will take slightly more power from your motors.

The Y axis gives you a max rpm of 1800, which is fine.

[Crunch]

Your X axis is quite long for 16mm - You'll get a 12mm root diameter on these, which means assuming you use a BK and a BF, you'll have a max speed of 1000rpm before whipping. With the 10mm pitch you're okay because it sets your max rapids of 10m/min - definitely wouldn't want to go 1605 though! A 20mm screw instead will give you a max rpm of 1260 which bumps your possible rapids up to 12.6m/min, but will take slightly more power from your motors.

The Y axis gives you a max rpm of 1800, which is fine.

That is where I started with 2010 on x axis
To stop whip as I had read so much.
The more I read the harder the decisions.

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[AndyUK]

That is where I started with 2010 on x axis
To stop whip as I had read so much.
The more I read the harder the decisions.

Well it was routercnc who said stick with the 16mm due to the added intertia of the 20mm. The man has built four of these things, he knows what hes doing.

I'm saying they'll work, but realise that they'll limit your rapids more than 20mm will. Personally I'd be more than happy with 10m/min rapids - You'd need some pretty strong motors to get up there anyway with a 100kg gantry.

[Crunch]

I was going to order from Fred at BST
He has offered machining the ends for pulleys.
He also offered better bk/bf bearings.
Is this the bearings you are talking about?

Thanks for advice

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[Clive S]

I was going to order from Fred at BST
He has offered machining the ends for pulleys.
He also offered better bk/bf bearings.
Is this the bearings you are talking about?

Thanks for advice

Sent from my SM-G900F using Tapatalk

Yes those are correct bearings. Just tell Fred the f length you require but as I have said the ball screw length includes the f length . Its an easy mistake to make.

So just order say ball screw machined both ends 1610 x 1200 with f length of 30mm

(where 1200 is the total length)

For the avoidance of doubt my router has twin screws twin motors and the screws are 1450mm overall. Motors nema 23 . without any problems.

[Crunch]

Yes those are correct bearings. Just tell Fred the f length you require but as I have said the ball screw length includes the f length . Its an easy mistake to make.

So just order say ball screw machined both ends 1610 x 1200 with f length of 30mm

(where 1200 is the total length)

For the avoidance of doubt my router has twin screws twin motors and the screws are 1450mm overall. Motors nema 23 . without any problems.

Are your ball screws 1610 or 2010 ??
How heavy is your gantry, roughly ??

[Clive S]

Are your ball screws 1610 or 2010 ??
How heavy is your gantry, roughly ??

1610 and about 70kg



there are two 1000x60x60 x5mm box section behind the front plate on the gantry.

Also you don't need the screw to be the full length of the machine

[pippin88]

I've had very good experience buying from Fred.

Why 1605 on the Z?