PDA

View Full Version : Bridgeport clone 3 or 5 hp



Barty
01-13-2014, 02:17 AM
I am looking at getting a new mill. I have a choice of 3 or 5 horepower. Is there any practical advantage to going to 5 hp or is 3 hp generally good enough?

Barty

LKeithR
01-13-2014, 02:26 AM
There are "Bridgeport" clones and then there are "Bridgeport CLones". From the specs I've looked at weights can vary by close to 1000 lbs. and I'm thinking that the heavier ones might handle 5 HP but 3HP is plenty for the smaller ones. I have a "mid-sized" clone with a 3 HP motor and I really don't think that it could handle more power than that...

.RC.
01-13-2014, 06:15 AM
Depends on what you want to do..... From what I have seen the 5hp heads are quite bigger and heavier then the generic bridgeport with the 3 3/8" diameter quill...

The 5hp I have has a 105mm diameter quill which is just over 4 1/8"..

Of course all this comes at a price.... Which is more then you will pay for the generic bridgeport...

John Stevenson
01-13-2014, 07:07 AM
Best to get a 5HP then you can rip those Timex quill drive gears out in a heartbeat instead of a 3HP one slowly crunching them up.

wierdscience
01-13-2014, 08:13 AM
It depends on what type work you are doing.If it's just general small parts machine work the 3hp is probably adequate.If you are doing Marine or heavy machinery work go with the 5hp.If the two mills have different spindle tapers same logic would follow unless one uses more common tooling.

lakeside53
01-13-2014, 12:54 PM
5hp helps if you are going to use a vfd... but the typical BP style Knee mill just isn't built to apply that much at the spindle. The later clones with the 10x54 tables are way heavier, but the ram, knuckle and head haven't materially changed from the original.

The original BP J-head came out with a 3/4 hp motor, then 1 hp. When the varispeed came out, it initially had a 1.5hp motor but was quickly replaced with a 2hp after complaints - the vari-speed sucked power so you got less at the spindle than the 1hp. Later they revised the 2hp specification to "2 hp continuous, 3 hp for 20 minutes".

Toolguy
01-13-2014, 01:12 PM
I've got 3 HP motors on 2 CNC bed mills with Bridgeport type heads. They do 99% of everything I want to do in high range. Anything else is easily handled in low range.

GT1
01-13-2014, 02:26 PM
I tend to stay with 3HP 3 phase motor. One can use single phase power with a VFD to power the 3 phase motor and get the ability to vary the speed and the 3 phase motor should be smoother. It comes in handy while power tapping. I don't believe they make a VFD to use a single phase input and get a 3 phase 5HP output.

lakeside53
01-13-2014, 02:30 PM
"They" do make true (not derated) 5hp out single phase in, but it's more $. Polycom is one manf.

I do almost all of my work with a 3hp motor on varispeed head and vfd (cnc'd mill). Rarely do I need to go to low ratio, but I do wind down the upper range to 1200 or 2100 as required, and I've hogged a lot of steel. if it didn't have the vari-speed head and ran just with the vfd, I'd probably get the 5hp to reduce belt-ratio changes.

Ohio Mike
01-13-2014, 10:45 PM
I am looking at getting a new mill. I have a choice of 3 or 5 horepower. Is there any practical advantage to going to 5 hp or is 3 hp generally good enough?

Barty

Both are overkill for an R8 knee mill. You'd need a 40 taper head but even then the machine may be a bit to springy. Save the money and spend it somewhere else.

.RC.
01-14-2014, 06:49 AM
Both are overkill for an R8 knee mill. You'd need a 40 taper head but even then the machine may be a bit to springy. Save the money and spend it somewhere else.

Too springy? Rubbish.... :D Yes that is an ISO40 spindle taper... And it even does horizontal milling...

http://users.beagle.com.au/lathefan/20131013_202522.jpg

http://users.beagle.com.au/lathefan/20140113_071254.jpg

John Stevenson
01-14-2014, 07:25 AM
Jabut it's not a Bridgeport.