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[技术] 自制车床

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发表于 2013-10-30 09:22:21 | 显示全部楼层 |阅读模式
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自制车床

自制车床


Custom Rambling Rose Engine & Ornamental Lathe
Headstock and Spindle
The headstock of the Rambling Rose Engine pivots on steel 60 degree points in brass sockets. Preload is adjustable. Plastic bearings assure long wear and minimum friction. The head can be locked in the central position for ornamental index work by a rod with a quick release ball joint fitting connected to the rear rubber rest.
The spindle has a 0.5" through hole for a drawbar and the spider has a #2 Morse Taper (MT-2). The chuck adjusting spider back and thread cutting timing belt drive gear are heat pressed fitted permanently on the spindle. The index wheel is secured by a set screw which controls the preload on the main spindle bearings.
We added 1/4" aluminum stiffner plates to each side of the web of the "I" beam headstock avoiding having to weld a custom headstock. This is a very stiff machine.
The back end of the spindle is 1" diameter with 12 threads per inch for the brass nut securing the cam(s).



自制车床

自制车床

 楼主| 发表于 2013-10-30 09:23:29 | 显示全部楼层
Chuck Adjusting Spider
Roland Hege and I have designed, specifically for a Rose Engine, a spindle to chuck adjusting spider for very fine adjusting of the chuck and work to the center of rotation of the rosette cam. This will allow corrections for any of the Rose Engine systems (rosette cam, spindle or chuck) that might not be exactly true with the spindle rotation. When doing very light cuts of a few thousandths of an inch, the work absolutely must rotate true or the error will obvious in the work. This is especially true when making light cuts in plastic or metals.
The chuck spider allows adjustment between the spindle center and the work center in all three axes. An 8.5 degree turn of an adjusting screw moves the spindle 0.001". So, fine adjustment is very easy. It does not take but a few thousandths run out anywhere in the Rose Engine from the cam to the workpiece to show in delicate cuts.
The chuck adjusting spider and timing belt drive were heat shrunk onto the spindle. Brass tipped set screws are used in the spider to keep from damaging the adjustment surfaces and ensuring smooth accurate adjustments. The spindle head is threaded 1" x 8 tpi common to wood turning lathes and has a Morse taper(MT-2) for specialized chuck jigs. The front part of the spider can be replaced with another spider front to change the spider thread size or add other accessories directly to the spider.
Several things can cause run out and the effect can be additive:
The cam center hole is not cut in exact center of the valleys of the rosette cam.
The cam hole is bored too large. If the hole is only bored 0.003" too large the run out could be as much as 0.006¨.
The chuck seats differently on the wood turning lathe spindle used to rough cut the workpiece than it seats on the Rose Engine spindle.
Dirt on either the roughing wood lathe spindle threads or the rose engine spindle threads.It is a real luxury to be able to easily and precisely center the workpiece with the cam action. We consider a chuck adjusting spider an absolute necessity for accurate Rose Engine work.
How to adjust the spider:
The spider can be quickly adjusted if adequate measuring surfaces are cut on the workpiece. First, lock the Rose Engine headstock so it can not rock. The axial adjustment is accomplished with the set screws on the back of the spider and aligns the line through the center of the spindle to be parallel with the line through the center of the work. To accomplish this the workpiece must have a flat surface on the edge of the face of the work to indicate (measure with an indicator). The maximum and minimum values are noted, the indicator is set to "0" at the value half way between and the back set screws are adjusted to the "0" value. The indicator should show the same reading as the spindle and workpiece is rotated with the headstock rocking motion fixed.
Second, unlock the spindle and install the cam that will be used to cut the pattern. The radial adjustment is accomplished with the set screws on the sides of the spider and aligns the work center line to correspond to the spindle center line. To accomplish this the workpiece must have a small portion of the outside of the work piece cut as a cylinder measuring surface. While rotating the spindle and workpiece the values of the indicator on the outside of the cylinder for each of the cutting positions (rosette cam valley positions) are noted and the same maximum and minimum procedure as above is used to center the work piece.
Now, the workpiece is exactly centered to the cutting action dictated by the rosette cam and any misalignment's are corrected. It takes less time to do than to explain.


自制车床

自制车床


Index and phasing system
The 36 hole index wheel is fixed to the spindle by set screw.   When doing ornamental work he head is stock is prevented from rocking with a rod connecting the headstock to the rear rubber platform. A quick release fitting on the headstock allows easy locking and unlocking.   The side of the index wheel toward the chuck and the vernier holes are used to secure the spindle in any of 360, or one degree, positions.   This results in 0.017" positioning ability on an 2 inch diameter work piece.   Smaller increments can be adjusted with the rubber or cutter height if necessary.   The one degree vernier adjustment works exactly like the "spin index" tool commonly used in metal working.
Each Rambling Rose Engine custom rosette cam has 1/3 and 1/8 phase alignment holes drilled either 1/4" or 1/8".   The index wheel has both 1/8" and 1/4" cam index holes in a 6" diameter to accommodate Jon Magill's MDF cams and other custom rosette cams.   The rosette cam can be repositioned in repeatable increments (phases) of a cam lobe phase in relation to the work.   Some custom Rambling Rose Engine cams also have 20 vernier holes allowing the rosette cam to position in any of 720 or 1/2 degree positions in relation to the workpiece when doing Rose Engine work.

自制车床

自制车床
 楼主| 发表于 2013-10-30 09:24:05 | 显示全部楼层
Rosette Cam
The Rambling Rose Engine is designed for a 9.5" maximum dimeter rosette cam.   Most custom cams are designed and cut close to the maximum size.   The bigger the cam the easier the spindle head motion will be. This is especially true for radical rosette cam designs.
The rosette cams are also drilled with 1/8 and 1/3 phase adjustment index holes so different indexed spiral rates or pattern repeats can be obtained in relation to the rosette cam lobe phase.   Simply unscrew the knurled brass cam nut and change rosette cam, add rosette cams or change the phase of the rosette cam.   This design allows use of as many as three rosette cams or combination of rosette cams at the same time.
The shape of a rosette cam can be determined by doing a little geometry and drafting using the desired final design size and shape and rosette cam diameter. This procedure is reviewed in an article by Amateur, "Making A Rosette from a Pattern", in the Society of Ornamental Turners Bulletin #46 page 22 March 1972.   In summary, one complete phase of the rosette cam shape must be cut. This can be done by hand or any method you can devise.   I used a milling machine and band saw to cut several.   My friend, Roland Hege, cut several Sine wave shapes for me with a CNC milling machine.   If one rosette cam lobe can be somehow formed, the rose engine index feature can be utilized to repeat that one cam lobe around the a rosette cam with the rose engine itself.   A rosette cam design can easily be cut inverted with the Rose Engine by clamping the rubber on the rubber rest on the opposite side of the cutter and duplicating a cam.   The rosette cam lobes then become valleys and the valleys become lobes.   The the valley cut of a rosette cam will not have a smaller radius than the radius of the cutter.

自制车床

自制车床


Round belt drive system
The hand crank has a 3" radius handle which allows steady slow turning if necessary. The high count, high rise or sharp pointed cam lobes need to be turned very slow to produce a smooth cut. The actual cranking ratio is 9 turns of the crank to 1 turn of the spindle. One revolution per minute for the spindle is not uncommon.
A very important feature of the RRE is the location of ball bearing round drive belt idler pulleys.   The torque vector or rotational force of hand cranking is directed exactly through the spindle head pivot point by the idler pulleys.   This keeps the spindle head in perfect balance no matter how large the torque forces originating from irregular hand cranking or resistance from high rise rosette cam lobes.   Therefore, none of the cranking force will add to the spring tension force keeping the rosette cam in contact with the cam lobe.   The hand cranking forces will not add to the force of the rubber climbing the rosette cam lobe.   This minimizes the cam lobe disengagement from the rubber or cam hop and much less spring pressure is required for consistent cam to rubber contact. The routing of the drive belt determines the amount of cranking force that is directed through the headstock into (or away from) the rubber rather than into spindle cranking force.
A round belt is used to assure smooth vibration free cranking action. The crank is located at the mid point of the spindle head for convenient cranking motions. The secondary drive belt tension is controlled by spring pressure on a ball bearing idler pulley block.

自制车床

自制车床

 楼主| 发表于 2013-10-30 09:25:33 | 显示全部楼层
Rubber assembly
The rubber assembly is the round ways frame bracket and supports the left spindle head pivot point. Front and rear rubber positions are designed for 3/4" square rubbers that contact the rosette cams mid center of the rubber or 3/8" above the rubber platform.   Any size rubber can be used so long as the rosette cam contact point can be shimmed to 3/8" height over the rubber platform.
We are using Ultra High Molecular Weight Polyethylene (UHMWPE) for rubbers. It's almost as slick as Teflon and cuts and machines very nicely with sharp tools. We get it in 3/4" square bars and cut it to 4" lengths and whatever end shape needed.
Polyethylene (UHMW) Rectangular Bar 3/4" Thick, 3/4" Wide.
"Ultra high molecular weight polyethylene, is a very tough material, with the highest impact strength of any thermoplastic presently made." "It has a very low coefficient of friction, is self-lubricating, and is highly resistant to abrasion (15 times more resistant to abrasion than carbon steel). Its coefficient of friction is" ... "comparable to that of Teflon, but UHMWPE has better abrasion resistance than Teflon. It is odorless, tasteless, and nontoxic." (quotes from Wikipedia)
This seems to me like the very best material to use for a friction rubber since it is so easily machined and has such a low coefficient of friction which results in negligible wear to the rosette cams and the rubber itself. Also, the price of $0.62 each plus shipping for a simple rubber is difficult to beat.
We plan to make a ball bearing rubber and, expect it would have the lowest friction of anything we could use if the radius of the ball bearing did not alter the result we were trying to obtain from the rosette pattern.

自制车床

自制车床


X-Z Compound Table
The X-Z compound table was integrated into the structural frame or ways of the RRE, eliminating the need for a table. We used left hand acme thread lead screws so a clockwise turning of the adjusting wheel would result in normal machine tool movement of the compound tables. The 10 threads per inch count of the lead screws result in one complete turn moving the table 0.100 inches. The adjusting wheels have adjustable dials calibrated with 100 divisions per revolution. Each division will move the table 0.001 inch.
The round and square tool holders are mounted on a goose neck type of mounting to allow extended horizontal and vertical locations of the cutting tool, keeping the overall dimensions of the Rambling Rose Engine compact.
The ways are hardened and ground for accuracy and wear resistance and the tables have precision plastic bearings. Any length ways and lead screws could have been used for either the Z-axis or X-axis compound tables.
Note X-Y-Z-axes:
In metal working machine speak, when standing in front of the machine, the X-axis moves in a front to back direction, the Z-axis moves in a left to right direction along the main ways and the Y-axis moves in a up and down direction. We use this standard in this Rose Engine information.

自制车床

自制车床

Cutter and Motor and Vibration dampening
The Rambling Rose Engine is designed to accommodate various types of cutter tools.   A goose neck tool holder will clamp 5/8" diameter and 1/2" square cutter tool mounting brackets.   The goose neck will extend the cutter up or down and in a 3.5" radius circle, extending the possible cutter position.   The goose neck can be easily replaced with a metal lathe quick change tool post if desired.
Cutting frames with integrated motors and overhead motor drive cutting frames can be used.
When weight is not a consideration, the Rambling Rose Engine uses lead shot bags for the ultimate in vibration dampening.


 楼主| 发表于 2013-10-30 09:26:34 | 显示全部楼层

自制车床

自制车床


Table or bed
The Rambling Rose Engine utilizes two hardened and ground round ways as both the structural frame and X-Z Compound ways, greatly reducing the weight of the overall machine.   If mobility and compactness were not as much of a concern, the main ways and Z-axis compound lead screw could easily be longer and larger diameter.
The RRE has walnut legs with independently adjustable rubber feet.

自制车床

自制车床


Hand crank
The hand crank rotates in a 6" diameter circle which allows steady slow turning if necessary. The high count, high rise or sharp pointed cam lobes need to be turned very slow to produce a smooth cut. The actual cranking ratio is 9 turns of the crank to 1 turn of the spindle. One revolution per minute for the spindle is not uncommon.
A round belt is used to assure smooth vibration free cranking action. The crank is located at the mid point of the spindle head for convenient cranking motions. The tung oiled walnut handle rotates freely on the crank arm.


 楼主| 发表于 2013-10-30 09:41:52 | 显示全部楼层

自制车床

自制车床


Universal cutting frame
This universal cutting frame is designed to fit in the round 5/8" diameter boring bar tool holder of a quick change tool post commonly used on metal lathes. The cutter head holds a 3/16" round HSS cutting tool and can cut a radius of from 0.6" to 1.6". It has a 1" adjusment for it's drive belt length. All bearings are ball bearings. It can cut over 4" deep into a hollow vessel. The design is modular so that multiple cutting heads and arms can be used for other size cutters.
These are "as built" drawings. The CAD drawing system requires exact measurements. Some dimensions can be rounded as needed. I made a change in the second UCF I built not shown on this drawing. I made the large drive pulley the same dimension as the smaller one. The allen head of the belt adjusting 1/4" bolt is very close to the large pulley in this drawing.

自制车床

自制车床

ucf1.part1.rar

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自制车床

ucf1.part2.rar

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自制车床

 楼主| 发表于 2013-10-30 09:44:43 | 显示全部楼层
Overhead drive system
The universal cutting frame is driven by a 1/2 HP variable speed motor through an overhead round 4mm round belt drive system. When the belt is on the bigger drive pulley the overall drive ratio is one turn of the motor gives 2.1 turns of the cutter head. The overhead can be adjusted for any location or angle of the cutting frame within the capacity of the Rose Engine itself.

自制车床

自制车床


Have Rose Engine, will travel
After Roland Hege and I demonstrated our shop Rose Engines this year for our wood turning club and we decided we wanted a Rose Engine that would be mobile enough to easily move around for Rose Engine demonstrations yet stiff enough to produce good work. After much brainstorming we developed the following design criteria for our Rambling Rose Engine. We fabricated and constructed it ourselves in June and July 2008. The drawings are available as PDF files for non commercial personal use only.Rambling Rose Engine Design Criteria:
Weight - Mobile weight less than 50 pounds including chuck, tool post and cutting frame. (It will fit in a 32"L x19"W x13"H box)
Spider - integral fine axial and radial adjusting spider for the chuck with 1" x 8 threads per inch, MT-2 taper & draw bar
X-Z Compound - integral X-Z axis compound w/ 0.001" calibrated index-able dials.   Positive adjustable stops for ornamental work.   We plan to incorporate rotation of the X-Z compound to allow cuts along a taper.
Rubber - front and rear rubber positions
Speed - 9 to 1 cranking ratio for slow speed control.
Phase - Ability to phase the rosette cams to the spindle (work piece) to 1/3, 1/4 or 1/8 cam lobe phases. Soon - very fine, repeatable phase adjustment between the rosette cam and the spindle (work piece).
Multiple cams - change cams quickly and easily and utilize up to 3 rosette cams at one time with independent indexing or phasing to each other and the work piece
Vibration - Rose Engine rocking motion with headstock and tool post vibration dampening
Capacity - Work capacity 10" diameter and 7.5" length.
Tool post - can be repositioned in 3.5" radius from any X-Z position and raised 1" or lowered 0.5 from spindle center. 5/8" round and 9/16" square tool holding capacity.
Ornamental - Can lock spindle with vernier holes in 1 degree or 360 positions for ornamental decoration work. Soon - very fine repeatable adjustment between the index wheel and the spindle (work piece).
Threading - We plan to incorporate internal and external thread cutting capacity w/ standard 10 tpi w/ others optional.
Building the Rambling Rose Engine design for your ShopFor use in your shop, you are not so interested in light weight as we are so the first design criteria will be eliminated. We suggest the following changes to the design to make the machine more rigid for bigger profile drilling cutters. We have included the drawing for the steel tube headstock as headstock3.pdf.

headstock3.pdf (59.87 KB, 下载次数: 538)
 楼主| 发表于 2013-10-30 09:56:02 | 显示全部楼层

自制车床

自制车床

主轴头计划

I am a hobby wood worker with some limited hobby experience in metal work.   Designing my custom Rose Engine and Ornamental Lathe required quite a bit of research since not much information exists.   You will find here photographs of my prototype Rose Engine and also design criteria, progress photographs and notes for my second generation custom Ornamental Rose Engine.The Rose Engine and Ornamental Lathe will rock and pump with either same side as cutter or opposite side from cutter rubber contact with the rosette cam or cams.   The rosette cam is easily changed and can be indexed within 1/2 degree to the spindle and work piece.   It has a 16 inch diameter work capacity, uses standard 1.25¨x 8tpi chucks, and is easily transportable to another lathe bed.   For ornamental design work, the spindle can be indexed to any combination of 720 positions.
The new and improved Rose Engine and Ornamental Lathe was ready for testing in early November 2007.   I update this site as I make progress, particularly the ¨Fabrication Notes¨.

 楼主| 发表于 2013-10-30 09:58:46 | 显示全部楼层
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headstock2.pdf

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crankpulley.pdf

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handle.pdf

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handlewasher.pdf

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 楼主| 发表于 2013-10-30 09:59:35 | 显示全部楼层
headstockpivotbushing.pdf (30.34 KB, 下载次数: 537)
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