In the next section, we will elaborate on the use of slots for overcoming the overconstraint problem through a sample part using geometric dimensioning and tolerancing principles defined by the ASME standard 1. Use of Slots – A GD&T Example. As we saw earlier, slots allow us to avoid overconstraint while having greater precision.
- Repair My Slot Machine
- How To Machine A Precision Slot Cars
- Slot Machine Parts And Repair
- Fixing Slot Machine
- Old Slot Machine Repair
1. A precision concrete and asphalt slot cutting machine, comprising:
a) a self propelled unit;
b) a blade platform;
c) a slot cutting blade positioned within the blade platform; and
d) at least one pivot arm with a first end pivotably attached to the self propelled unit and a second end pivotably attached to the blade platform, said pivot arm allowing said blade platform to tilt from side to side in a direction transverse to the path of travel of said self propelled unit.
2. A concrete and asphalt slot cutting machine as in claim 1, wherein said blade platform has first, second, third and fourth sides with said first and second sides being opposite each other and said third and fourth sides being opposite each other and wherein there are two of said pivot arms, both of which have a first end pivotably attached to said self propelled unit with a first of said pivot arms having a second end pivotably attached to said first side of said blade platform and a second of said pivot arms being spaced from said first pivot arm and having a second end pivotably attached to said second side of said blade platform.
3. A concrete and asphalt slot cutting machine as in claim 2, wherein each of said pivot arms is L shaped with a long leg of each L shaped arm being pivotably attached to said self propelled unit and a short leg of each L shaped arm being pivotably attached to said blade platform.
4. A concrete and asphalt slot cutting machine as in claim 2, and further comprising:
a) a frame extension extending outward from said self propelled unit;
b) a cross bar interconnecting said pivot arms; and
c) a hydraulic piston & cylinder unit with a first end attached to said frame extension and a second end attached to said cross bar.
5. A concrete and asphalt slot cutting machine as in claim 1, and further comprising:
a) a first wheel supporting bar with a first wheel supported near a first end thereof and a second wheel supported near a second end thereof;
b) a second wheel supporting bar with a third wheel supported near a first end thereof and a fourth wheel supported near a second end thereof;
c) a first pivot frame attached to said third side of said blade platform and pivotably supporting said first wheel supporting bar about a first pivot axis; and
d) a second pivot frame attached to said fourth side of said blade platform and pivotably supporting said second wheel supporting bar about a second pivot axis.
6. A concrete and asphalt slot cutting machine as in claim 5, and further comprising:
a) a blade drive shaft attached to said slot cutting blade;
b) drive means for driving said blade drive shaft in a rotary motion; and wherein
c) said first pivot axis of said first wheel supporting bar and said second pivot axis of said second wheel supporting bar are aligned vertically with said blade drive shaft.
7. A concrete and asphalt slot cutting machine as in claim 5, wherein said first and second pivot frames are vertically adjustable with respect to said third and fourth sides of said blade platform, respectively, such that the cutting depth of said slot cutting blade is adjustable.
8. A precision concrete and asphalt slot cutting machine, comprising:
a) a self propelled unit;
b) a blade platform attached to said self propelled unit, said blade platform including first, second, third and fourth sides with said first and second sides being opposite each other and said third and fourth sides being opposite each other;
c) a slot cutting blade positioned within the blade platform;
d) a first wheel supporting bar with a first wheel supported near a first end thereof and a second wheel supported near a second end thereof;
e) a second wheel supporting bar with a third wheel supported near a first end thereof and a fourth wheel supported near a second end thereof;
f) a first pivot frame attached to said third side of said blade platform and pivotably supporting said first wheel supporting bar about a first pivot axis; and
g) a second pivot frame attached to said fourth side of said blade platform and pivotably supporting said second wheel supporting bar about a second pivot axis, said first and second pivot axes being in alignment with each other.
9. A concrete and asphalt slot cutting machine as in claim 8, and further comprising:
a) a blade drive shaft attached to said slot cutting blade;
b) drive means for driving said drive shaft in a rotary motion; and wherein
c) said first pivot axis of said first wheel supporting bar and said second pivot axis of said second wheel supporting bar are aligned vertically with said blade drive shaft.
10. A concrete and asphalt slot cutting machine as in claim 8, wherein said first and second pivot frames are vertically adjustable with respect to said third and fourth sides of said blade platform, respectively, such that the cutting depth of said slot cutting blade is adjustable.
11. A concrete and asphalt slot cutting machine as in claim 8, and further comprising:
a) at least one pivot arm with a first end pivotably attached to the self propelled unit and a second end pivotably attached to the blade platform.
12. A concrete and asphalt slot cutting machine as in claim 11, wherein there are two of said pivot arms, each with a first end pivotably attached to aid self propelled unit, a first of said pivot arms being pivotably attached to said first side of said blade platform and a second of said pivot arms being spaced from said first pivot arm and being pivotably attached to said second side of said blade platform.
13. A concrete and asphalt slot cutting machine as in claim 12, wherein each of said pivot arms is L shaped with a long leg of each L shaped arm being pivotably attached to said self propelled unit and a short leg of each L shaped arm being pivotably attached to respective sides of said blade platform.
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14. A concrete and asphalt slot cutting machine as in claim 12, and further comprising:a) a frame extension extending outward from said self propelled unit;
b) a cross bar interconnecting said pivot arms; and
c) a hydraulic piston & cylinder unit with a first end attached to said frame extension and a second end attached to said cross bar.
15. A precision concrete and asphalt slot cutting machine, comprising:
a) a self propelled unit;
b) a blade platform with first, second, third and fourth sides with said first and second sides being opposite each other and said third and fourth sides being opposite each other;
c) a slot cutting blade positioned within the blade platform;
d) a pair of pivot arms, each with a first end pivotably attached to said self propelled unit, a first of said pivot arms having a second end pivotably attached to said first side of said blade platform and a second of said pivot arms being spaced from said first pivot arm and having a second end pivotably attached to said second side of said blade platform;
e) a first wheel supporting bar with a first wheel supported near a first end thereof and a second wheel supported near a second end thereof;
f) a second wheel supporting bar with a third wheel supported near a first end thereof and a fourth wheel supported near a second end thereof;
How To Machine A Precision Slot Cars
g) a first pivot frame attached to said third side of said blade platform and pivotably supporting said first wheel supporting bar about a first pivot axis; and
h) a second pivot frame attached to said fourth side of said blade platform and pivotably supporting said second wheel supporting bar about a second pivot axis.
16. A concrete and asphalt slot cutting machine as in claim 15, wherein each of said pivot arms is L shaped with a long leg of each L shaped arm being pivotably attached to said self propelled unit and a short leg of each L shaped arm being pivotably attached to said blade platform.
17. A concrete and asphalt slot cutting machine as in claim 15, and further comprising:
a) a frame extension extending outward from said self propelled unit;
b) a cross bar interconnecting said pivot arms; and
c) a hydraulic piston & cylinder unit with a first end attached to said frame extension and a second end attached to said cross bar.
18. A concrete and asphalt slot cutting machine as in claim 15, and further comprising:
a) a blade drive shaft attached to said slot cutting blade;
b) drive means for driving said blade drive shaft in a rotary motion; and wherein
c) said first pivot axis of said first wheel supporting bar and said second pivot axis of said second wheel supporting bar are aligned vertically with said blade drive shaft.
Slot Machine Parts And Repair
19. A concrete and asphalt slot cutting machine as in claim 15, wherein said first and second pivot frames are vertically adjustable with respect to said third and fourth sides of said blade platform, respectively, such that the cutting depth of said slot cutting blade is adjustable.
Computer Aided Design (
CAD) software is now the default tool for drawing perfectly rendered objects on a computer screen, which are then transferred to a manufacturer to make the actual part. But there’s a danger in thinking that anything that can be designed can just as easily be made. Software programs are capable of drawing dimensions that are far more accurate and exacting than can be achieved by machine tools and materials in the real world. But what do we mean by words like “accuracy” and “precision” when we’re talking about how parts are made and how closely they come to the ideal generated on the computer?To clear up any confusion about terminology, we want to clarify what accuracy, precision and tolerance mean. Then we can transform this knowledge into practical advice which will help your designs go from the computer to the factory floor more quickly, easily and with better results.
Accuracy: Degree of Conformance to a Known Standard or Value
The international standard for length is the meter, and its value is a universal one based on the distance that a beam of light travels in a certain fixed period of time. So, accuracy is the degree to which a measurement or movement in space conforms to a systematic standard or one of its derivatives – typically the millimeter or micron for metric measurements.
Thus, when a CNC machine tool is touted as being highly accurate, this means that if it’s programmed to cut a piece of metal 40mm long, then the machine actually does that. The more accurate it is, the closer it gets to exactly 40mm, with no error.
Useful information: More accurate is not necessarily better for many applications. Achieving ever greater degrees of accuracy costs time and money for diminishing returns. In addition, getting high accuracy in one area of a design often requires sacrificing accuracy elsewhere. But rest assured that modern CNC cutting tools are reliably accurate for the vast majority of projects.
Precision: Repeatability of a Measurement or Action Without Generating Random Errors
For CAD software, it’s safe to assume that design drawings are absolutely precise. They will reliably repeat any design feature with perfect fidelity as many times as you wish. This is one of the great labor-saving wonders of computer design.
In the factory, precision for a machine or process is the ability to repeat an action the same way every time with no introduced or random error. Precise machining, or precise workmanship, is a testament to controlling the process and not deviating – regardless of whatever the measurement or process may be. This is often confused with accuracy and indeed the two terms are casually used interchangeably. However precision refers more to repeatability.
Useful information: In this case, precision is in the hands of the manufacturer, and this is really the performance you’re looking for. It’s precision that ensures your product comes out the same way every time, which is one of the essential features we refer to as “quality” for volume production. How do we measure precision? By specifiying tolerance.
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Tolerance: Allowable or Predictable Deviation From a Standard
Image Credit: Starrett
All machine tools will have a degree of free play or vibration in them – they must, or else they would be frozen, inert blocks. The tolerance therefore specifies the deviation away from a known value, expressed as a “+/-” number. So, if we have a machine tool that claims a tolerance of “+/- 1 mm”, this means the tool will potentially introduce a deviation of one millimeter with every cut or pass. Could be an extra millimeter, or too short by a millimeter or some fraction thereof.
Useful information: What’s true for the machine tool is also true for your product. You don’t want parts to fit together too tightly, without clearance. This would mean they are immovable, or impossible to assemble. Different metals and plastics expand and contract with temperature and moisture, so good design means allowing for this natural movement. And draft angles are necessary when parts need to be removed from an injection mold tool. We will discuss with you the recommended tolerances on all critical dimensions for your project, which will depend greatly on material, manufacturing process and part geometry.
Taken together, this means that accurate work comes close to the standard, precise workmanship is reliably accurate over and over again, while tolerances are controlled to within a small, acceptable degree of variability from one part to another.
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For more information on this subject, we have a Design For Manufacturing page which gives more tips and techniques to avoid the most common design errors. And this chart specifies the tolerances you can expect when working with many kinds of injection molding plastics. Want to know still more? Contact us today for a free quotation and design review.
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