TheSamba.com :: View topic - Bridgeport Mill

Sun May 29, 2016 11:52 pm

Setting up my Series 1 Bridgeport mill today. I trammed the table/head already and doing a couple of practice cuts on a junk head and block.
Using a RJE cutter that works well for surfacing cyl. decks but a little chatter on head. 150 RPM's is what speed i'm using.

Any suggestions? I hear/read that WOHLAUPTER 3 boring head is great but what about Narex, Criterion or Big Kaiser?

Mon May 30, 2016 12:18 am

The farther OUT you extend the head and crank out the table toward you the less RIGID the machine is, so to avoid chatter, keep things CLOSE!

I think you could have done a better job securing the head tot he table too, the hold downs look to be a bit too far away from centered over the rocker box, but I can't really see.

Yes a facing head like the wolfencopterwhatsit is really nice, and they cost a lot too. You want to resurface heads with a lot of AREA another choice is do it in two steps. You can do the piston size with one cut then do the cylinder cut stop .001 short, and should be no chatter.

Mon May 30, 2016 8:22 am

Minimize all unnecessary extension: ram, knee, & quill.
If not already in the habit of locking-down the table w/ clockwise-loading, it would be wise to start now.
Verify proper cutting edge relief for soft mat'ls (alum, etc), & don't forget a minimal nose radius.
Drop-down to 80 RPM for heads, & always clamp them down from the inside of the exhaust ports. This orientation is on the strongest axis, & it also allows one to clearance-cut on the 1st fin in the same setup.
The Wohly is a precision boring head, & way overkill for a simple head resurf operation. Most importantly: it's not rigid at all.
That depicted "RJE" toolholder: perfect type for both resurfacing & boring cases/heads. One can even "step-bore" a case (ala 92's, etc) by setting-up w/ 2 AL-8s, 180* apart.
G' luck

Mon May 30, 2016 12:07 pm

FeelthySanchez wrote: Minimize all unnecessary extension: ram, knee, & quill.
If not already in the habit of locking-down the table w/ clockwise-loading, it would be wise to start now.
Verify proper cutting edge relief for soft mat'ls (alum, etc), & don't forget a minimal nose radius.
Drop-down to 80 RPM for heads, & always clamp them down from the inside of the exhaust ports. This orientation is on the strongest axis, & it also allows one to clearance-cut on the 1st fin in the same setup.
The Wohly is a precision boring head, & way overkill for a simple head resurf operation. Most importantly: it's not rigid at all.
That depicted "RJE" toolholder: perfect type for both resurfacing & boring cases/heads. One can even "step-bore" a case (ala 92's, etc) by setting-up w/ 2 AL-8s, 180* apart.
G' luck
Good point! I will drop down my RPM. If I retract the ram, maybe I have to tram the table again? I dont extend the quill though.
I leave it all the way up. I also raise the table toward the cutter rather than bringing down the quill when I resurface the head.

Mon May 30, 2016 1:41 pm

bring the table up and then lock it ,it might be moving,lower rpm,use as little stroke as possiable with the quill,you might try tightening the quil lock when you get to depth, or snug it a little just before. I have a head plate that holds through the pushrod hoiles&also ex ports and the intake side too. dont overtighten and bend things as that can cause chatter too. I dont know what the exzact answer is.just make some changes and see what youyr set up likes.
if your tramed in corectly moving the quill will not change that. but tighteniong the table lock will change location oh so slightly......depending on your machine condition.and I suppose depending on how you tramed it in it may affect that.but on a 4" wide cut you would have to be out a good bit to make enough for an issue. Ive seen heads that were out oh so far and never leeked(with gasketed serface).but...that dosent make it right so ,,,you have the machine to do it right so do it right. now...where's the dro& servo drive..... :wink: your machine looks nice.

Mon May 30, 2016 1:56 pm

[/quote Mr. Okrasa] ...... If I retract the ram, maybe I have to tram the table again? I don't extend the quill though. I leave it all the way up. I also raise the table toward the cutter rather than bringing down the quill when I resurface the head.[/quote]

Re re-tram: generally "no" in this case, assuming the ways sport no more than normal wear.
But, since we now know that you're properly feeding w/ the knee, I must ask: When initially trammed, was the knee un-clamped/unlocked?
If so, fine. This would be the correct mode for a head/case resurfacing operation. If not, it might be a minor issue.

Chatter can be a fickle beast & sometimes difficult to diagnose/cure.
Until the learning curve flattens-out, one can't go wrong here w/ "ASAP" (Slow AP) - assuming correct AL-8 reliefs/geometry & fixture rigidity.
Always bear in mind that the feedrate (aka: our "human input" here) must be firm, steady & constant: as I've found most B'port chatter to be a function of cutting tool "dwell" or stalled feeding.

All else looks great & I noted the proper quill pos'n in above pix - a good move. Locking the quill @ it's highest (home, or rest) point is always advised unless needed for tapping, etc.

While on the topic of locking axes, I must ask: Are ya in the habit of loading both leadscrews & locking both the X & Y axes when resurfacing in this manner? Reason being: It helps very much w/ rigidity.
If (after all the above tweaks) chatter is still present: it might be time to tighten the gibs a bit. (Another pretty simple task).
BTW, that's a nice looking S1 refurb. If ya might provide the s/n, I could advise when she was first "born".

G' luck & regards,
Phil T.

Mon May 30, 2016 3:00 pm

You are using a single blade cutter. You will need that sucker really humming. I had a bunch of chatter issues till I ran the speed up. The berg mill tool instructions said between 800-1000rpm. I tried it, and it cuts amazing now. No chatter unless the cutter starts loading up. I also use a few shots of wd40 right before I start the wide facing cut to keep the galling down.

Make sure your feed rate is very constant, and like mentioned above, don't dwell at any one point.

Some older heads that have been welded on, or really overheated also cut pretty hard.

Here is a video of Ray Vallero (rip) cutting a head. Check how fast his cutter is spinning.

Brian

Mon May 30, 2016 3:06 pm

Make some steel full flow covers!

Mon May 30, 2016 4:30 pm

atleast put a cheep dro on the z (quill) so you can get what you want eazely. diferent heads have different carateristicks....and different harmonics, fine the speed your setup likes.it's a good thing there is no issue with deadheads to practice on. and always double check locks and clamping!!!as well as the draw bar& dont ferget to remove the drawbar wrench, that sucker hurts. :shock: :wink:

Tue May 31, 2016 7:45 am

dont forget to squirt a little oil in the oilers in the head. i like to slide the quill stop up and a few turns to help lock it down. looks like a nice mill

Wed Jun 01, 2016 4:00 pm

I find that a little very light oil ( like spindle oil) squirted a the cutting surface helps cut down on the chatter. ( p.s. Not referring to Mark BTW lol)

Wed Jun 01, 2016 11:59 pm

mark tucker wrote: atleast put a cheep dro on the z (quill) so you can get what you want eazely. diferent heads have different carateristicks....and different harmonics, fine the speed your setup likes.it's a good thing there is no issue with deadheads to practice on. and always double check locks and clamping!!!as well as the draw bar& dont ferget to remove the drawbar wrench, that sucker hurts. :shock: :wink:
I installed my new SERVO power feed. Trying to figure out what 3 axis DRO I want to buy.

Thu Jun 02, 2016 4:30 pm

Brian_e wrote: Check how fast his cutter is spinning.

Brian

This is what we call a 'bastard cut' in the machining circuit. :lol: The tolerance on this should be 0.010" or worse.

If I ever see a 'machinist' doing this cut on MY machines, I will freaking beat him w/ a baseball bat. This is not the way they teach you in school. Imagine machinining a precision shaft and the rough cuts and final finish are rolled into one. What kind of accuracy do expect from that workpiece.

YOU DO NOT ABUSE THE MACHINES like this. They are supposed to last a lifetime. Use them w/ care.

There should be some rough passes and then maybe a final finish cut to do an accurate machining job.

If you clamp the heads, use the MIDDLE PORTION of each side of the gasket rail. If you use the exhaust ports, you will not be center on the gasket rail there will be too much bias on the bottom surface -so the head will tilt. The head can come loose during a cut. This is a good way to lose an eye ...or finger. I know you are excited to get going on machining stuff, but safety....safety...safety.

If you are doing a boring job, it will be stupid to lock the quill since it has to move up and down. All you will do is wear the pad and quill until it will not lock down worth shit. Then you have to R/R that whole quill.

The only reason to lock down the quill is if you have to do a milling pass when the quill has to maintain its position.

You said you have trammed the head to the table, but do you know how much 'runout' is there? on the quill bearings? on the leadscrews? How much does the knee change your 'tramming' when you clamped/unclamped?? You have to adjust your gibs until you have the least runout without binding the table on its X or Y or Z axes.

Chatter is created when you have too much toolhang, rigidity of the tool, how sharp the toolbit (proper rake angle and cutting relief if any), also lubrication on the workpiece. The quill speed.

It is a lot to process but you will get there.

So is this 3-phase or single phase power? I build my own coverters to run all my 3 phase machines.

GEt you also the Bridgeport manual and study it. Burn the info into memory.

Wear eye protection. No drinking while machining.

Thu Jun 02, 2016 4:38 pm

Also on the Bridgeport, there is no direct dial to read the depth of cut other than that threaded quill-stop. So use this quill stop if you are doing decking surfaces and has to match.

Get the manual.

Thu Jun 02, 2016 4:57 pm

nsracing wrote: Also on the Bridgeport, there is no direct dial to read the depth of cut other than that threaded quill-stop. So use this quill stop if you are doing decking surfaces and has to match.

Get the manual.
Wouldn't it be better if I have a DRO on the Z axis and lock the quill? Raise the table with the head clamped to the cutter to maintain rigidity
on the quill by leaving it up? I rather trust the DRO on the Z rather than using the threaded quill stop. Thoughts?

The motor on my Bridgeport is a 3 phase.

BTW, I'm leaning towards the Acu-Rite VUE 3 Axis Digital Readout Systen for my Bridgeport. Is this a "good one"?

Thu Jun 02, 2016 4:58 pm

you also need to get the"safty" handle that freewheels,$10-30 on flebay) push it inward to lock it and use manuly. it keeps anything including you from getting cought in the handle as it rotates by the drive......and...be sure there is nothing at the other end that might get cought or...ran into when it reaches the end. and always remember if your machining somethen ,on that there is clearance when it gets to the end if it,s hanging off. I have a 9x49 mill and it neer the door.....plenty of room... unless I have something extra long on it then I just raise the door up, that maximized my shop space.most shops angle them if you have more than one mill so they dont impead on each other. but my other mill is on the other side of the shop.so...no interfearance. a little thinking can go a long way.and if you make some special tools/tooling....mark it well and make a place for it or you may end up looking for it lator to realize you made something else out of it :shock: been there done that, now everything gets it's own job box(usualy wooden witch is great as you can wd or light oil the parts& the box absorbs it and keeps them from rusting.)also AC more and other hobby shops have wooden hindged boxes of many sizes&shapes that are oh so cheep. took boxes arnt real good for tooling that usualy wont fit good. you also need a coax indacator to center up perfectly.cheep on flebay as are oh somany tools&jigs. but be very aware it's more addictive than vw shit!!!!! also....yup theres more. the r8 collets are good, but... a er 32 set is better and in metric!!! .040" each with a +- of .040" makes them oh so awesome and fit everything...also on flebay or the china site bangood.(Ive been getting some stuff from them, better prices, cheeper or free shipping)for the same things. I think I have 2mm to 22mm set.and there are m,any diferent length &size holders to choose from.or a r8 holder. they have cheep nuts too.

Thu Jun 02, 2016 5:13 pm

With the direction you have the head mounted, it is not necessary to have it trammed perfect front to back, it can he a few thou off and make no difference. It should be trammed as good as possible left/right, because that is the direction you are moving the table.

Did you indicate the HEAD before cutting it? Old heads warp, the bottom of the valve cover rail pulls in toward the engine. The amount of shims you end up putting here to get the head level is proportional to how much they have suffered.

NSR has very strong passion, as usual, so you have to dial that back 50% to get to reality :wink:

Thu Jun 02, 2016 5:15 pm

DROs are for pussies! :lol: :lol: :lol:

Don't go crazy on attaching digital stuff to start off. Unless you are made of money by all means.

Just find you some Trav-A-dials. These were made for Bridgeport type knee mills.

There is no fine-feed for the Z-axis - will not be fine enough to do precision work. Besides, the quill head is already designed to do all the adjustments for any cut you desire.

Although, they make a quill digital readout cheaply. But if you decide to use this electric stuff you might have to remove the threaded quill stop. You will lose the clutch-disengage if you do. You need this safety feature left alone in the quill if you ask me.

Thu Jun 02, 2016 5:23 pm

Your mill is variable speed so easy on speed changes or you will find out how much work it takes to replace that belt.

I have had many mills in my lifetime. There is nothing like the old V-belt durability.

There is nothing more irritating to me than to see someone abusing a beautiful machinetool.

Fri Jun 03, 2016 6:37 am

when you switch from low gear to hi gear spin the spindle by hand a little back amd forth, to make sure its in gear completly( you will hear it click if its not enguaged all the way, otherwise it will make a grinding noise that will get everyones attention and sevreal funny comments as well.