Motion when locking the axis

[Former Member]

Motion when locked??? Some what of a contradiction of terms.

Generally when locking you are removing all play by reducing the clearance to the point that it is tighter (smaller) than what it clamping against.

So the bigger question, if no one has asked, have you checked where the play is coming from and might you be chasing down the wrong thing?

 

[PeterT]

Also when I asked them to use an alternate shipping method since Canada post was experiencing unreasonable delays they refused.

Interesting, I would have thought the other way around. Most USA vendors insist on the couriers (UPS/Fedex..). By shipping USPS they are normally doing you a favor because it might cost you 5$ fee landed in Canada whereas the couriers could cost you 40$ in fees for a box of zero value, duty free air. Anyways if CanPost was an issue at that time, it was worth the inquiry. But for many USA dealers, Canada is a pita & they are not making money for the time & effort.

 

[Susquatch]

whereas the couriers could cost you 40$ in fees for a box of zero value, duty free air.

Hahahaha! Soooooo true!

 

[Eyecon]

Frankly.......... PUT THAT SCRAPER AWAY!

Seriously, I would not use that thing on anything till I knew a whole lot more about what's wrong.

Even then, I'd prolly practice for a few years on something I didn't care about.....

While I'm do not have years of experience scraping, I did successfully scrape in a couple of angle plates and straight edges flat and square. The plan was to blue the dovetail and check for contact along the already scraped gib, this would help me confirm that the gib taper angle/general fitting is off. Based on that, I was only planning on making adjustments to the gib not the ways. Since I'm getting a replacement gib blank anyway, I figured this would be good practice and possibly a temporary solution before working on the replacement blank that has to be cut and scraped anyway.
One of the reasons I bought this machine is that it has ground-to-scraped surfaces on all 3 ways/dovetails. The gibs on all 3 axis are also scraped to mate with ground dovetails. All scraped surfaces also have the proper oil groves machined into them for the one shot oiler system.

 

[PeterT]

When the gib is bottomed out on its lower surface, do you have the same amount of vertical gap between the top of gib & underside of slide on both ends of the gib? (vs more gap on one side or the other?)

Also, the way it is right now, are you able to adjust the gib with the 2 adjustment screws so that the table can become overly tight in slide axis? Or are you running out of adjustment so its always loose to some degree?

 

[Dabbler]

Ya, just put the replacement spindle away for now.

yes. +1. Use what you have and discover how it performs first.

 

[Dabbler]

Interesting, I would have thought the other way around. Most USA vendors insist on the couriers (UPS/Fedex..).

I had a long chat with Matt about duties and fees, and convinced him to try USPS/Canada Post for smaller shipments. Obviously he has found this better than the couriers for smallish packages.

@Eyecon I'm sorry about the duty delays, but it is far better than paying a courier (you know who you are) 120$ brokerage fee for an USD$ 80.00 shipment. True story.

 

[DavidR8]

I had a long chat with Matt about duties and fees, and convinced him to try USPS/Canada Post for smaller shipments. Obviously he has found this better than the couriers for smallish packages.

@Eyecon I'm sorry about the duty delays, but it is far better than paying a courier (you know who you are) 120$ brokerage fee for an USD$ 80.00 shipment. True story.

If he will switch to USPS/Canada Post for small items it will make buying from PM more attractive.

Thanks!

 

[Former Member]

I posted this before want to get the best rates and not dinged on Brokerage? UPS Worldwide Expedited! Not a good rate, use Netship and use UPS Worldwide Expedited.

I ship constantly world wide 99% of the time UPS can't be beat on my account, Netship comes close.

Worse comes to worse have them give you the package size and wt and send them the label.

 

[PeterT]

I posted this before want to get the best rates and not dinged on Brokerage? UPS Worldwide Expedited! Not a good rate, use Netship and use UPS Worldwide Expedited.

Not to turn this post into another shipping discussion, but I thought this UPS Worldwide thing got hashed out in post below. Using the UPS-WW chart in post#29 I cant see how the shipping cost of say a 5 pound item of $97 to $353 depending on the state/region comes anywhere near close to what USPS would charge for the same item (est 21$ depending on location)? Yes, UPS-WW is a faster delivery mode which always comes at higher cost regardless of shipper, but who can justify this kind of shipping fee? If what you saying is get a business account in order to drive some unstated discount? - but don't you need a 'business' with GST# etc? I have personal UPS & Fedex accounts, they charge me the listed rate. What am I doing wrong? What box to I need to tick to get low cost rates?

UPS Charges

I'm noticing few changes in AliExpress shipping options. Not sure if its the vendor or value or general improvements, but some vendors offer 'faster' delivery for a fee. But I have never seen UPS specified as an option. Some items from China are arriving within weeks & as much as half of the...

canadianhobbymetalworkers.com

 

[Susquatch]

While I'm do not have years of experience scraping, I did successfully scrape in a couple of angle plates and straight edges flat and square. The plan was to blue the dovetail and check for contact along the already scraped gib, this would help me confirm that the gib taper angle/general fitting is off. Based on that, I was only planning on making adjustments to the gib not the ways. Since I'm getting a replacement gib blank anyway, I figured this would be good practice and possibly a temporary solution before working on the replacement blank that has to be cut and scraped anyway.

I didn't mean to discourage you from trying your hand at scraping. I guess I was really trying to discourage you from doing ANY REMEDIATION AT ALL until you are dead certain that you know exactly what is wrong. Once you take metal off, you can't put it back. Yes, I know you have two Gibb plates now. But I wouldn't try fixing either one of them just yet. Even if you blue them and find a high spot, how do you know that the high spot is really a high spot and not something else wrong? And how do you know that scraping wouldnt make that other thing worse?

This and other questions all need to asked and answered methodically. But then again, I am not well known for jumping into anything without checking for aligators, snakes, and bloodsuckers first!

Let me put it this way, what do you have to lose by going slow? And while you ponder that question, also ask yourself what you have to lose by going fast?

Just my two cents.......

 

[Former Member]

Then use Netship. My rates are significantly less and so are Netship's about 70% of list for UPS.

Consumers get soaked.

I'm shipping 12lbs in 1-2 days for US$28-30 with full Insurance.

 

[Eyecon]

I had a long chat with Matt about duties and fees, and convinced him to try USPS/Canada Post for smaller shipments. Obviously he has found this better than the couriers for smallish packages.

@Eyecon I'm sorry about the duty delays, but it is far better than paying a courier (you know who you are) 120$ brokerage fee for an USD$ 80.00 shipment. True story.

Believe me I felt the pain of brokerage fees from both FedEx and UPS before, I totally get it This is not in anyway PM’s fault. I called CBSA and they said the Mississauga branch where my package is had “severe infrastructure issues” and to expect 2 additional weeks of delay…shame on our agency for not having a contingency plan!

To clarify though: in the case of zero cost replacement parts, couriers DO NOT charge customs clearance fees. I deal with Carbide3D in CA all the time and they always FedEx overnight replacement parts to me and I do not have to pay anything. Same thing happened once with UPS from a US tool supplier where I got my Vertex rotary table, they sent me the missing indexing discs and tail stock valued at 200usd + and I didn’t have to pay anything because it was appropriately declared as zero cost warranty replacement part.

 

[Eyecon]

Let me put it this way, what do you have to lose by going slow? And while you ponder that question, also ask yourself what you have to lose by going fast?

I’m totally on board with this approach, I’m just not sure what else I need to do to figure out why the gib is skewing in place as shown in the video other than blueing it. Also based on what PM support told me, what they shipped is a blank: a much longer piece of grey cast stock with the appropriate tapper ground. It needs to be scraped and cut to length before it can be used as a gib. This is why I was thinking to at least start with the bluing process to try and figure out why the gib is moving up and down, try the scrapping process based on what the bluing shows and see if the problem is fixed. This way I don’t have to risk ruining the gib blank.

Based on the rough kinematic setup I did in Fusion360, the only way the gib can move up and down as shown in the video is a) there is a high spot region in the center of the gib and it’s only making contact in the center leaving the wide and narrow ends free to move or b) the overall taper angle is slightly shallower than the mating surface effectively causing it to only make contact at the narrow end, leaving the wide end I was trying to snug free to move up and down as it did. The static face of the gib will be first blued against a surface plate to make sure that it is at least flat. All this assumes both castings dovetails are flat. I believe that @PeterT already said that is it very unlikely that the casting have any issues and that the gib fitting is the most likely culprit. This is what I’m hoping the bluing process will show.

Am I missing other steps in the troubleshooting process?is there something else I should try before taking the machine apart and attempting to blue the impacted dovetail/gib?

I’m really trying to learn the appropriate setup and troubleshooting procedure so I very much welcome the advice.

 

[PeterT]

Then use Netship. My rates are significantly less and so are Netship's about 70% of list for UPS.
Consumers get soaked.
I'm shipping 12lbs in 1-2 days for US$28-30 with full Insurance.

what website are you logging into? I get this

 

[RobinHood]

….figure out why the gib is moving up and down,…

The Y-axis gib is moving up / down when you tighten / loosen the adjusting screw because it is not tall enough. The contact point of the adjusting screw is on the left hand side of center. A tightening action (clock wise rotation) lifts the gib up. When you back off the screw (ccw rotation), the gib sees a downward force and thus moves back down.

I would put a little brass shim above the gib at the screw. About 1/2” long or so should be plenty. The shim needs to be thick enough to fill up the head room. Then the gib will no long lift up while tightened.

Even with a gib not tall enough (as long as it does not lift) should not impede proper function if the taper angle is correct and matches both mating dove tail surfaces.

Installing a new gib that is also not tall enough will not help the “uplift“ problem.

So I was curious why there was no complaint about the X-axis gib…

Here is the reason: the gib taper is right to left. The adjusting screw is in front. This results in a downwards force exerted during the tightening process. The gib will not lift even if it is not tall enough.

 

[Dabbler]

Based on the rough kinematic setup I did in Fusion360, the only way the gib can move up and down as shown in the video is a) there is a high spot region in the center of the gib and it’s only making contact in the center leaving the wide and narrow ends free to move or b) the overall taper angle is slightly shallower than the mating surface effectively causing it to only make contact at the narrow end, leaving the wide end I was trying to snug free to move up and down as it did. The static face of the gib will be first blued against a surface plate to make sure that it is at least flat. All this assumes both castings dovetails are flat. I believe that @PeterT already said that is it very unlikely that the casting have any issues and that the gib fitting is the most likely culprit. This is what I’m hoping the bluing process will show.

There is also another manufacturing defect, because the gibb is too short. There is supposed to be a curved cove that captures the gibb screw, so that when you tighten the gibb, it seats against the rounded surface of the gibb screw, preventing any more than a couple of thou of movement/lift.

When I was working on my hartford mill, there was only around .003 clearance total in the vertical direction... This is just enough to collect oil, but clear enough to not rub on the flatway.

 

[Former Member]

what website are you logging into? I get this

View attachment 33627

I have used them, so its always at the top of my mind.

Netparcel.com

Shiptime.ca

 

[RobinHood]

Blueing will give you an indication of surface contact. I would try the x-axis first. I believe you said it was a bit better? This would give you an indication of how much care was taken at the factory. If it shows a reasonable result, check the Y-axis. If it is about the same, then there is not much you can do about it unless you re-scrape both gibs to try and get an even better fit.

Another thing to consider is the fact that the Y-axis usually has less surface area than the X (The dove tails and thus the gib are shorter). So you may actually see the whole saddle “twist” about Y.

 

[Eyecon]

@RobinHood @Dabbler thank you so much for the valuable insight!

This is the kinematic setup I created in fusion360 to try and understand the root cause of the issue(if it's indeed a significant one).

The blue and green components are the sides of the dovetail(of course for simplicity I modelled the blue side as a 90deg dovetail aka just a flat surface, the green side was modelled with a 60deg angle so I get a better understanding of the compound angle when the lifting occurs). The orange component is the tapered gib. The lift movement I'm getting is represented by a revolute joint that allows mating faces of the orange gib to freely rotate on the respective faces of the blue and green dovetails. If I ground the green and blue components so they can't move in a any direction, there is no way for me to rotate the gib despite the fact that it's not constrained in motion by anything above or below it. So below is the ideal state: the gib is perfectly fitted to match both dovetails on either side.

The only way for the gib to lift is for either on of its mating faces to have the wrong angle(or not be perfectly flat) or the the same with either side of the dovetails.

Shown below is the gib lifting up(or down depending on how you look at it), and this is only possible if the blue "dovetail" is not 90deg to the ground plane in this case since the green dovetail is fixed flat to the ground. Therefore if we assume the casting dovetails are perfectly flat, the only way for the gib to lift would be that it doesn't have full contact on both sides, so either the static side is not flat or has the wrong taper angle, or the sliding side is not flat or has the wrong taper angle.

@RobinHood understanding that the gib is allowed to move in my case because it's not tall enough, the above leads me to conclude that the root cause of the lift/slop is that it's not flat or taper angle is slightly off. Even if I shim it from above and stop is from lifting, it would still not be making full contact and therefore causing the excessive slop that I reported in the beginning of this thread despite being pushed far enough to make the motion in Y tighter than it needs to be. Does this logic make sense? Did I misunderstand your shimming suggestion?

In the case of the X axis, I do not need to push the gib in as much to remove the slop in the table. I understand that it's a longer gib and therefore would have more friction even if it's not perfect but I was able to reduce the slop in X and get smooth/easy movement on the wheel but not on Y.