Perfect @RobinHood!
I think that explains everything for me. Maybe that will be the first part I make on the new mill!
I think that explains everything for me. Maybe that will be the first part I make on the new mill!
-
Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.
New to me Bridgeport Mill
- Thread starter Susquatch
- Start date
I finished configuring my VFD for the existing motor on my Bridgeport. As per advice from members I set the minimum speed at 1/4 (15 Hz) and the max at 75 Hz.
The motor seems to run just fine like that. There is no detectable vibration or noise at 75Hz and at 15Hz the big built in fan pushes a lot of air and runs very cool
https://streamable.com/ysfzez
At this point, I'm almost certain that the vast majority of the noise my Bridgeport makes is from the sheeve belt. You can watch it flopping around when it's noisy and see it smooth out when it's quiet. Too bad it was run against the springs for a while. I'll replace it if I end up deciding to keep the Bridgeport.
Still don't have the new motor for the Hartford. Looking like Tuesday right now.
The motor seems to run just fine like that. There is no detectable vibration or noise at 75Hz and at 15Hz the big built in fan pushes a lot of air and runs very cool
https://streamable.com/ysfzez
At this point, I'm almost certain that the vast majority of the noise my Bridgeport makes is from the sheeve belt. You can watch it flopping around when it's noisy and see it smooth out when it's quiet. Too bad it was run against the springs for a while. I'll replace it if I end up deciding to keep the Bridgeport.
Still don't have the new motor for the Hartford. Looking like Tuesday right now.
Just measured the actual spindle speed on my Bridgeport. When the sheeves are set as slow as they can go, it's running about 84 rpm about 40% faster than the claimed 60 rpm. The same is true at all extremes - ie min/max in both low and high gears. So it's not just an offset on the speed dial. It really is running a lot faster than it should.
To confirm this, I also did a manual count at low speed with a stop watch. Got exactly the same result at 84 rpm.
Wondering if that could be a function of the belt that was damaged running it against the spring on the drive sheeve....
Or is this just normal?
As per my posts on @architect's thread https://canadianhobbymetalworkers.com/threads/bridgeport-project.3521/post-48818, I also made a really nice tool to remove and install the quill cap. Worked like a charm!
To confirm this, I also did a manual count at low speed with a stop watch. Got exactly the same result at 84 rpm.
Wondering if that could be a function of the belt that was damaged running it against the spring on the drive sheeve....
Or is this just normal?
As per my posts on @architect's thread https://canadianhobbymetalworkers.com/threads/bridgeport-project.3521/post-48818, I also made a really nice tool to remove and install the quill cap. Worked like a charm!
I see. I guess I just assumed that since the BP was designed and built in the USA before the advent of VFD's, the ratings would all be based on the 60Hz system.
But no biggie, if that's the way it is then I won't get my nickers in a knot over it. If I end up keeping the BP, I'll prolly run mine at 50Hz too.
I decided to use the BP the way it is to make a custom pulley key for my Hartford.
That meant checking the bed surface and tramming it.
What a surprise awaited me. Despite how badly hen pecked the bed was, it was flat! I couldn't find any high spots at all. On inspection, it was obvious that it had been regularly stoned.
Also, I found it was only out 2.5 thou left to right and 4 thou on the Nod over a 5" span. Not bad at all considering how much travel it has endured, but easy to fix, so I did.
That meant checking the bed surface and tramming it.
What a surprise awaited me. Despite how badly hen pecked the bed was, it was flat! I couldn't find any high spots at all. On inspection, it was obvious that it had been regularly stoned.
Also, I found it was only out 2.5 thou left to right and 4 thou on the Nod over a 5" span. Not bad at all considering how much travel it has endured, but easy to fix, so I did.
In preparation for milling a motor key for my Hartford Mill, I asked a bunch of questions about approaches for doing it. @RobinHood recommended a 1/2" end mill at 1200 rpm.
So I dialed that in on my Bridgeport using a combination of belt positioning and VFD frequency setting. In the process, I discovered something quite informative.
I began by looking for a nice smooth quiet speed on the pulley setting. There are several. I had already noted that they seemed to correspond with reduced belt flopping around.
Then I tried dialing in a VFD setting to hit 1200 rpm. That's when it hit me. The mill stayed quiet no matter what speed the motor ran at.
After that observation, I am even more convinced that all the noise the BP makes are the result of belt flopping around in the sheeves. After all, that is the only thing that changing speeds did not change.
Its too bad it was run with the belt against the springs for so long. But I think that's a pretty straight forward repair.
Anyone see any flaws in that rationale?
So I dialed that in on my Bridgeport using a combination of belt positioning and VFD frequency setting. In the process, I discovered something quite informative.
I began by looking for a nice smooth quiet speed on the pulley setting. There are several. I had already noted that they seemed to correspond with reduced belt flopping around.
Then I tried dialing in a VFD setting to hit 1200 rpm. That's when it hit me. The mill stayed quiet no matter what speed the motor ran at.
After that observation, I am even more convinced that all the noise the BP makes are the result of belt flopping around in the sheeves. After all, that is the only thing that changing speeds did not change.
Its too bad it was run with the belt against the springs for so long. But I think that's a pretty straight forward repair.
Anyone see any flaws in that rationale?
Last edited:
I forget, did you have this belt out for inspection? Perhaps just a new belt will solve the problem?
I never actually removed it. I discovered that it was running on the sheeve spring, removed the motor, compressed the springs the way they are supposed to be done, changed the front pulley to largest separation, and reinstalled the motor.
It was a night and day difference at the time - as one should expect.
Although it was much quieter, as time passed, I became more and more aware of the minor noise I recorded and posted earlier.
A while after that I was watching the belt through the slot above the speed dial and noticed that the belt flopped around a lot more at certain speeds. That's what led to the observation later on that it really didn't flop at certain speeds, it flopped at certain sheeve spacings - or more accurately DIDN'T flop around at certain spacings.
So yes, I hold out VERY HIGH HOPES that merely changing the belt will totally clobber what noise there is left there. But I'm in no hurry to do it. It's actually very good as is. If I decide to sell the BP, it will get sold with the belt as is. If I decide to keep it, I'll order a new belt for it then.
That decision looms closer ever day. My first parts shipment arrived today......
There are essential parts for both mills in that order. For the BP, it includes the feed speed selector components, the table locks, the turret pinion handle, and one turret bolt. I only bought what I considered essential parts to facilitate a decision.
Once I have decided, then I will complete the machine I keep and also decide how much to fix on the other one before selling it.
I encountered a new Bridgeport problem today. I was going to drill some motor bolt holes in my adapter plate when the quill handle suddenly stopped moving the quill.
It seems the quill handle key is all screwed up. I took it apart and found a little wee teeny tiny woodruf key that had moved into the center shaft and no longer engaged the clock spring bushing and the shaft.
Obviously that was like that when I bought it but I couldn't know until it moved enough to get disconnected.
I believe it is the wrong size key. But I don't know what is correct. The H&W website is in a bit of a mess right now. It looks like they are in the middle of changing it.
Anybody know what that is all supposed to look like?
It seems the quill handle key is all screwed up. I took it apart and found a little wee teeny tiny woodruf key that had moved into the center shaft and no longer engaged the clock spring bushing and the shaft.
Obviously that was like that when I bought it but I couldn't know until it moved enough to get disconnected.
I believe it is the wrong size key. But I don't know what is correct. The H&W website is in a bit of a mess right now. It looks like they are in the middle of changing it.
Anybody know what that is all supposed to look like?
I did a quick search to find a #3 key and stumbled on the charts below. Perhaps they will be useful to others.
That key looks a bit big compared to mine. But I will measure it in the morning. In any event, a bigger one than mine is definitely needed.
I'll give Fastenal a call in the morning to see if they have one.
When I removed the clock spring, another key (or a lengthwise piece of one), fell out from behind the spring itself. This one was square like a regular key, not semi-circular like a woodruff. It also has a small burr at one end of it that looks a bit like an unfinished broach stroke.
My first guess is that it is half of the regular woodruff key after it sheared. However, the shear surface is well polished which I would not have expected.
What is #11 in your attachment?
I had a chance to make some measurements and poke around a bit this morning. In my opinion, the small woodruff key is indeed a #3. All of its dimensions are a bit short of the minimums, but then again it is worn a bit.
The longer square key is not and never was part of that particular woodruff key.
The dimensions are as follows:
Woodruff Key:
0.473L x 0.190D x 0.124 thick
Straight Key:
0.770L x 0.116D x 0.115 thick
Shaft slot is 0.75 long
Here are a few photos:
If the woodruff is placed in the shaft slot, it literally drops below the surface of the shaft.
However, it does create a surface that a square key can sit on. Here is a photo of the slot, the woodruff inserted, and the resulting "stacked keys".
The sleeve will install on the stack, but it is a bit loose. I don't really see how the square key ended up behind the clock spring, but it isn't tight so Murphy may have put his hand to it. I'm much more inclined to think that the previous owner lost the square key and glued the woodruff in place so he could sell it. Perhaps the mill is the root of the way he treated his previous partners. He knew he would get caught sooner or later so he quit beforehand.
I see no point in replacing the #3 key or the square key as is. Although silver soldering them together is an option, I'm more inclined to try and make a custom key that combines both keys into one.
If I keep the Bridgeport, perhaps I'll get a new shaft for it some day.
So....... Anyone know what the proper procedure is for preloading the clock spring?
It looks like someone put the 2 keys together to try and replicate the correct key that maybe got lost. A #7 woodruff key would likely be correct as it is 1/4" taller than a #3 woodruff key.
Instructions to install the clock spring from my manual.
Instructions to install the clock spring from my manual.
This stack is only about 1/8" taller than the #3 alone. But I have to start somewhere and that seems as good as any.
I admit that I am surprised to learn that the clock spring is not supposed to lift the quill - just balance the weight. I would never have guessed that.
Thank you for the manual photos.
Yes that is interesting. I always thought my BP clone was sluggish on the return up. It doesn't stay in equilibrium, it does raise on its own (slowly). I guess its supposed to be this way for some reason. My only prior data point was my prior RF-45 mill which retracted quicker, more like a drill press.
Couldn't find a woodruff key today. Nobody in my part of the world had any stock. So I made my own on the lathe and then cut it in half and ground it to fit better than a purchased one would have. It was fun!
Installed the clock spring as per the instructions. 1.5 turns worked about perfect as a counterweight.
Back to making my first vise stop tomorrow and then 4 custom vise clamps for my Gerardi Vise after that!
Installed the clock spring as per the instructions. 1.5 turns worked about perfect as a counterweight.
Back to making my first vise stop tomorrow and then 4 custom vise clamps for my Gerardi Vise after that!
trlvn
Ultra Member
For next time, I've got a stash of various size woodruff keys. Not all sizes but quite a few. They came from an auction lot a couple of years ago.
Craig