Bridgeport Mills Diff between HP

[TB76Bronco]

I am looking at mills and I found one that is a 1 HP 9x42 series 1. What I am wondering is there any difference in the machine on the 1, 1 1/2 and 2hp machines? Are they all the same machine with different motors?

thanks

[TB76Bronco]

Hmm 53 views and no answers. I did some seaches on the internet and I can't seem to find an answer. Anyone know?

[PAToyota]

Wish I had an answer for you...

[87-toy]

same machine just more power you can take a bigger cut

[Upper2]

My Bridgeport Series II Special 2 hp is an 11" X 52" table.

[TB76Bronco]

So I should be able to take a 1hp motor off the mill and replace it with a 2hp if I end up wanting more power. Everything else is the same except the motor then?

[jnutter]

You probably won't want more HP. 1 HP is a lot when applied to a cutting tool.

[TB76Bronco]

Great thanks for the information everyone. I'm going to look at the mill tomorrow.

[Wicked_S10]

I am fairly certain that the 1hp head is the step pulley J head. It is not a bad head, but the step pulley design is a bit of a PITA if you need to change speeds a lot. The 1.5hp and 2hp motors were available on the vari-speed head which uses two variable pitch pulleys to adjust the spindle speed. The vari-speed head also has a back gear low range of 8.33:1. I believe the J head also has a back gear. There are even older head designs, like the M head, but I believe it used an even smaller motor, and had no back gear.

If you get a J head, you can overcome the frequent pulley changes by useing a VFD to drive the head. You are far better off using a VFD to convert to 3 phase then you are putting a single phase motor on it. Price will be about the same if you shop around, and a 3phase motor has a much more constant torque curve, faster starts, and easier reversal. A single phase motor has a constant 60hz ripple in the torque due to the nature of single phase AC, a 3 phase motor does not have the ripple because the three phases are all 120° out of phase with each other.

Later,
Jason

[LAME]

1HP is plenty. Most variable speed 2HP old Bridgeports I have see have loud ass, worn out, gears. I got rid of my 3ph 1 hp motor on my J-head, and converted it to a 1hp 90V DC motor with a pot. Infinite speed, runs on 115v AC, and none of that annoying gear noise I would have to deal with on a Series II varible. Conversion costs about the same as a phase converter.

[stainless steal dave]

a j head bridgeport would be a step pulley head where you have to move the belt to change spindle speeds. a 2j head would be a variable speed head- i believe they were offered in 1 1/2 and 2hp versions. i have both versions sitting in my machine shop. it does not look like the motors are interchangeable between the heads. the belt drive j head came in a high speed version 160 rpm-5400 rpm. this was needed when using small diameter end mills. most of the heads are the 80 rpm-2700 rpm versions-that would be my personal choice if i was shopping for a milling machine for garage/hobby use. j heads were also offered with a single phase 220 volt electric motor-all you had to do was plug it into a 220 volt electric dryer plug in your garage and it was ready to run. when you go look at the mill for sale make sure the key inside the spindle has not been stripped out of it. make sure the taper in the spindle is not torn up from chip dents because the operator was to lazy to wipe it clean before inserting a different size collet. indicate the inside of the spindle with a dial indicator on the inside of the taper to make sure it hasn't been seriously crashed and as a result the spindle is bent. run-out should be .0005 or less. test run the machine-make sure the head is run in back gear if lots of noise/rattling is heard pass on it or negotiate a much lower price. test run the power feed for the quill and make sure it works in both directions-up and down. most likely the gibs on the saddle of the machine will need to be adjusted to get rid of excessive wear and the lead screw nuts will need to be adjusted/replaced but it is a used machine and this is expected.good choice in selecting a bridgeport they are well supported as far as getting parts for them-and they have a better resale value over a used chinese or tiwan milling machine. good luck with your machine inspection-i hope it's a keeper and you get to buy it.

[JR]

I have a 1966 series I Bridgeport with a 1 hp motor and 8 speeds.
It's plenty enough power! Mostly I work with slow mill speeds where the torque mutiplication is huge. Power is just never a problem.

The vari speed robs power by design and is why they need more hp.

My 1 hp Logan lathe is vari speed and bogs down pretty easy.
But then again, I think lathes need more power than mills.

[TB76Bronco]

Thank you everyone for your help. I bought the mill its a 1hp series 1 Bridgeport J head. He is including a collet set some R8 tool chucks (not sure what they are called) and some end mills to get me started.

The table on the mill is pretty rough and has quite a few drill marks on it and is missing the knee crank. It is definatly not in perfect shape but it appeared to fit my needs and is in the right price range. Its hard to find mills in my area and for $1700 with no shipping I think I did pretty well. The others I've seen in the area are $3000 or so for not much better condition although they have had DRO's.

He included a vice he had but it has a bent screw or something and only opens about 1/2 way. So I bought a Kurt D875 angle lock with swivel base on ebay for $201.

I am looking at a VFD to handle the phase conversion and give me variable speed but I have not decided on what one to get yet. I posted a question on www.practicalmachinist.com about it.

[John-e Bravada]

Does anyone know what an old 9x42 variable speed Bridgeport weighs?

[Toddy]

Right at 2100#.

Toddy