I made a similar fixture where I was going to face off a plate of Delrin 10.5 x 15.25". Enough surface area to get good down force on the stock. I used several stops around the perimeter to locate the stock. All looked good but when I took the first facing pass of 0.5mm, the edges lifted and I lost vacuum. Seems the stress in the Delrin is very strong and combined with the coolant spraying under the edge was too much for it. I ended up adding some pitbull clamps around the part to hold it down. The vacuum held the part flat for a perfect face while the pitbull clamps kept it from springing up. Now I get a perfect 12.00mm thick Delrin plate out of the setup. "You don't need the vacuum if you have the pitbull clamps" Not true, the Delrin will not stay flat unless the vacuum is present. I've moved on to cutting in all the features on one side of the plate before removing the vacuum. Perfect parts!!
Yes! Delrin, UHMW, Nylon... These materials are notorious for having high stresses near the surface of the material. If the stress causes the part to warp with a force greater than 14 psi, then vacuum will barely be able to overcome it. One popular strategy to produce flat plastic parts is to take a light face cut, flip and face the other side. The stress in the skin will be removed and the part will be in a more rested state for further machining. Or use pitbull clamps like you mentioned, lol.
@@PiersonWorkholding Just to be clear, the vacuum is crucial to keeping the Delrin flat to the fixture, the pitbulls are only there to hold the corners down and are lightly tightened so as not to cause warping.
Newbie alert! Why can't you ground flat the part after machining it? Just to make sure I am seeing correctly: On the vacuum fixture ; the area outside the ""vacuum zone" is lower, right? Otherwise the tool would touch the fixture when doing the perimeter, right? By the way, how flat the black part needs to be? Thank you, Jorge
You want it as flat as possible. After all, you are mounting your 4th axis on it. And on a very long part, even slight unevenness at mounting side may become even few milometers at the other side.
@@rdc02271 I'm guessing probably no more than few microns. There may be few reasons why they grind it before. Raw stock have uneven surface and they would have to face it on a mill at least in 1st OP, which would take more machining time and after it surface won't be as perfect so they would have to put in on a grinder anyway. Also, I'm not sure, but there may be some locating features that have to be perpendicular to the the surface and if your surface isn't flat, it won't be perfectly perpendicular.
@@rdc02271 Blanchard grinding has very close control of the final thickness and flatness but is terrible at controlling the starting position of the first surface. It's best to grind first, machine second so all the chamfers and counterbore depths are accurate. Also, aluminum parts need to be blocked in from the sides which can ruin the finish of the perimeter.
@@PiersonWorkholding don't be obtuse, it's not a design requirement for the outside to have been done in a single setup. do the first op and most of the sides, flip, do the second op and the rest of the sides, no putting pins in and out, operator spends less time messing with fixtures.
Is the work envelope on the machine being used large enough to support a vac fixture big enough to do two parts at once? That would save the process of inserting the pins between ops. Also is a ground surface really necessary? A face mill may be a little slower but it keeps the work in house. Looking forward to the series.
If your surface isn't ground flat, you won't know where your 4th axis is. The 4th axis table can and will be tilted, which throws out the other accuracy of whatever else you got on there, and snowballs your errors.
The workflow is to run all parts Op1 then to insert pins once and run all parts Op2. However, we practice 1-piece-flow so these operations are done on 2 adjacent machines with identical vacuum fixtures.
@@PiersonWorkholding thanks for the quick response. I love mine by the way. Gets my HRC210 out of the work envelope and I have a lot more swing that allows me to use a 5th Axis dovetail tombstone.
I agree that some type of mechanical lock (like your pin) is the way to go for handling the side loads.
I made a similar fixture where I was going to face off a plate of Delrin 10.5 x 15.25". Enough surface area to get good down force on the stock.
I used several stops around the perimeter to locate the stock.
All looked good but when I took the first facing pass of 0.5mm, the edges lifted and I lost vacuum.
Seems the stress in the Delrin is very strong and combined with the coolant spraying under the edge was too much for it.
I ended up adding some pitbull clamps around the part to hold it down.
The vacuum held the part flat for a perfect face while the pitbull clamps kept it from springing up.
Now I get a perfect 12.00mm thick Delrin plate out of the setup.
"You don't need the vacuum if you have the pitbull clamps"
Not true, the Delrin will not stay flat unless the vacuum is present.
I've moved on to cutting in all the features on one side of the plate before removing the vacuum. Perfect parts!!
Yes! Delrin, UHMW, Nylon... These materials are notorious for having high stresses near the surface of the material. If the stress causes the part to warp with a force greater than 14 psi, then vacuum will barely be able to overcome it. One popular strategy to produce flat plastic parts is to take a light face cut, flip and face the other side. The stress in the skin will be removed and the part will be in a more rested state for further machining. Or use pitbull clamps like you mentioned, lol.
@@PiersonWorkholding Great video. I like your method of explaining things. Clear and concise.
@@PiersonWorkholding Just to be clear, the vacuum is crucial to keeping the Delrin flat to the fixture, the pitbulls are only there to hold the corners down and are lightly tightened so as not to cause warping.
Plastic and vacuum go hand in hand Ive found
✅ SmartPlate from video 👉 bit.ly/3zScO4g
Newbie alert!
Why can't you ground flat the part after machining it?
Just to make sure I am seeing correctly: On the vacuum fixture ; the area outside the ""vacuum zone" is lower, right?
Otherwise the tool would touch the fixture when doing the perimeter, right?
By the way, how flat the black part needs to be?
Thank you,
Jorge
You want it as flat as possible. After all, you are mounting your 4th axis on it. And on a very long part, even slight unevenness at mounting side may become even few milometers at the other side.
@@Stasiek_Zabojca what tolerances are we talking about
In terms of flatness.
Compared to the mill table , for instance.
And why ground flat the block before machining? ...
🤔
@@rdc02271 I'm guessing probably no more than few microns.
There may be few reasons why they grind it before. Raw stock have uneven surface and they would have to face it on a mill at least in 1st OP, which would take more machining time and after it surface won't be as perfect so they would have to put in on a grinder anyway. Also, I'm not sure, but there may be some locating features that have to be perpendicular to the the surface and if your surface isn't flat, it won't be perfectly perpendicular.
@@rdc02271 Blanchard grinding has very close control of the final thickness and flatness but is terrible at controlling the starting position of the first surface. It's best to grind first, machine second so all the chamfers and counterbore depths are accurate. Also, aluminum parts need to be blocked in from the sides which can ruin the finish of the perimeter.
Can someone please tell me a song name?
Carrolton-made for this
Eh this could just as easily be done in a vise
Nope. It's like you didn't even watch the video.
@@PiersonWorkholding don't be obtuse, it's not a design requirement for the outside to have been done in a single setup. do the first op and most of the sides, flip, do the second op and the rest of the sides, no putting pins in and out, operator spends less time messing with fixtures.
Is the work envelope on the machine being used large enough to support a vac fixture big enough to do two parts at once? That would save the process of inserting the pins between ops. Also is a ground surface really necessary? A face mill may be a little slower but it keeps the work in house. Looking forward to the series.
If your surface isn't ground flat, you won't know where your 4th axis is. The 4th axis table can and will be tilted, which throws out the other accuracy of whatever else you got on there, and snowballs your errors.
The workflow is to run all parts Op1 then to insert pins once and run all parts Op2. However, we practice 1-piece-flow so these operations are done on 2 adjacent machines with identical vacuum fixtures.
What is different in the new version of the Smart Plate from the one that I purchased last month?
The new version works for all brands of rotary units, not just Haas.
@@PiersonWorkholding thanks for the quick response. I love mine by the way. Gets my HRC210 out of the work envelope and I have a lot more swing that allows me to use a 5th Axis dovetail tombstone.